Device and method for enabling an orthopedic tool for parameter measurement

ABSTRACT

A system for enabling a medical device. The system includes a cradle having a magnet for generating a magnetic field. The cradle supports and aligns the medical device in a predetermined orientation. Medical device placed in the cradle exposes a magnetic sensitive switch to the magnetic field of the magnet that produces a change in state of the magnetic sensitive switch. Medical device further includes a switch, indicator, logic circuitry, delay circuit, and detect circuit for coupling a power source to electronic circuitry. In a first mode of operation the medical device can be turned on and then turned off. In a second mode of operation the medical device cannot be turned off after being turned on.

FIELD

The present invention pertains generally to surgical electronics, andparticularly to methods and devices for assessing alignment and surgicalimplant parameters during spine surgery and long-term implantation.

BACKGROUND

The spine is made up of many individual bones called vertebrae, joinedtogether by muscles and ligaments. Soft intervertebral discs separateand cushion each vertebra from the next. Because the vertebrae areseparate, the spine is flexible and able to bend. The vertebrae providea conduit for the spinal cord neural bundle. Together the vertebrae,discs, nerves, muscles, and ligaments make up the vertebral column orspine. The spine varies in size and shape, with changes that can occurdue to environmental factors, health, and aging. The healthy spine hasfront-to-back curves, but deformities from normal cervical lordosis,thoracic kyphosis, and lumbar lordosis conditions can cause pain,discomfort, and difficulty with movement. These conditions can beexacerbated by herniated discs, which can pinch nerves.

There are many different causes of abnormal spinal curves and varioustreatment options from therapy to surgery. The goal of the surgery is ausually a solid fusion of two or more vertebrae in the curved part ofthe spine. A fusion is achieved by operating on the spine and addingbone graft. The vertebral bones and bone graft heal together to form asolid mass of bone called a fusion. Alternatively, a spinal cage iscommonly used that includes bone graft for spacing and fusing vertebraetogether. The bone graft may come from a bone bank or the patient's ownhipbone or other autologous site. The spine can be substantiallystraightened with metal rods and hooks, wires or screws via instrumentedtools and techniques. The rods or sometimes a brace or cast hold thespine in place until the fusion has a chance to heal.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features of the system are set forth with particularity in theappended claims. The embodiments herein, can be understood by referenceto the following description, taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 illustrates a spine measurement system in accordance with anexample embodiment;

FIG. 2 illustrates a spinal instrument in a non-limiting example;

FIG. 3 illustrates a spinal instrument having integrated electronics ina non-limiting example;

FIG. 4 illustrates an insert instrument with vertebral components in anon-limiting example;

FIG. 5 illustrates a lateral view of the spinal instrument positionedbetween vertebrae of the spine for sensing vertebral parameters in anon-limiting example;

FIG. 6 illustrates a graphical user interface (GUI) showing an axialview of the spinal instrument of FIG. 5 in accordance with an exampleembodiment;

FIG. 7 illustrates the spinal instrument positioned between vertebra ofthe spine for intervertebral position and force sensing in accordancewith an example embodiment;

FIG. 8 illustrates a user interface showing the spinal instrument ofFIG. 7 in accordance with an example embodiment;

FIG. 9 illustrates a lateral view of the spinal insert instrument forplacement of the spine cage in accordance with an example embodiment;

FIG. 10 illustrates the graphical user interface showing the insertinstrument of FIG. 9 in a non-limiting example;

FIG. 11 is a block diagram of the components of the spinal instrument inaccordance with an example embodiment;

FIG. 12 is a diagram of an exemplary communications system forshort-range telemetry in accordance with an example embodiment;

FIG. 13 illustrates a communication network for measurement andreporting in accordance with an example embodiment;

FIG. 14 illustrates an exemplary diagrammatic representation of amachine in the form of a computer system within which a set ofinstructions, when executed, may cause the machine to perform any one ormore of the methodologies disclosed herein;

FIG. 15 illustrates components of a spinal instrument in accordance withan example embodiment;

FIG. 16 illustrates a spine measurement system for providingintervertebral load and position of load data in accordance with anexample embodiment;

FIG. 17 illustrates a spine measurement system for providingintervertebral load and position of load data in accordance with anexample embodiment;

FIG. 18 illustrates an exploded view of the module and the handle inaccordance with an example embodiment;

FIG. 19 illustrates a shaft for receiving a removable sensored head inaccordance with an example embodiment;

FIG. 20 illustrates a cross-sectional view of a female coupling of thesensored head in accordance with an example embodiment;

FIG. 21 illustrates an exploded view of a spinal instrument inaccordance with an example embodiment;

FIG. 22 illustrates a cross-sectional view a shaft region of the spinalinstrument of FIG. 21 in accordance with an example embodiment;

FIG. 23 illustrates a cross-sectional view of a sensored head region ofthe spinal instrument of FIG. 21 in accordance with an exampleembodiment;

FIG. 24 illustrates an exploded view of the sensored head region of thespinal instrument of FIG. 21;

FIG. 25 illustrates a cross-sectional view of the sensored head regionof the spinal instrument of FIG. 21 in accordance with an exampleembodiment;

FIG. 26 illustrates a spinal instrument and a cradle in accordance withan example embodiment;

FIG. 27 illustrates a knee insert and a cradle in accordance with anexample embodiment;

FIG. 28 illustrates a block diagram of a system to enable and disable amedical device in accordance with an example embodiment; and

FIG. 29 illustrates a state diagram of a medical device enabling circuitin accordance with an example embodiment.

DETAILED DESCRIPTION

While the specification concludes with claims defining the features ofthe embodiments of the invention that are regarded as novel, it isbelieved that the method, system, and other embodiments will be betterunderstood from a consideration of the following description inconjunction with the drawing figures, in which like reference numeralsare carried forward.

As required, detailed embodiments of the present method and system aredisclosed herein. However, it is to be understood that the disclosedembodiments are merely exemplary, which can be embodied in variousforms. Therefore, specific structural and functional details disclosedherein are not to be interpreted as limiting, but merely as a basis forthe claims and as a representative basis for teaching one skilled in theart to variously employ the embodiments of the present invention invirtually any appropriately detailed structure. Further, the terms andphrases used herein are not intended to be limiting but rather toprovide an understandable description of the embodiment herein.

Broadly stated, embodiments of the invention are directed to a systemand method for vertebral load and location sensing. A spine measurementsystem comprises a spinal instrument coupled to a remote display. Thespine measurement system can measure load, balance, and alignment toassess load forces on the vertebra. The spinal instrument can be anactive device having an electronic assembly and a sensorized headassembly that can articulate within a vertebral space. The sensorizedhead can be inserted between vertebra and report vertebral conditionssuch as force, pressure, orientation and edge loading. The spinemeasurement system further includes alignment circuitry. The alignmentcircuitry provides positional information for identifying an orientationand location of the spinal instrument. A GUI of the remote system can beused to show where the spine instrument is positioned relative tovertebral bodies as the instrument is placed in the inter-vertebralspace during the surgical procedure. The system can report optimalprosthetic size and placement in view of the sensed load and locationparameters including optional orientation, rotation and insertion anglealong a determined insert trajectory.

An insert instrument is also provided herein with the load balance andalignment system for inserting a vertebral component such as a spinecage or pedicle screw. The system in view of previously capturedparameter measurements can check and report if the instrument is edgeloading during an insertion. It shows tracking of the insert instrumentwith the vertebral component and provides visual guidance and feedbackbased on positional and load sensing parameters. The system showsthree-dimensional (3D) tracking of the insert instrument in relation toone or more vertebral bodies whose orientation and position are alsomodeled in 3D.

FIG. 1 illustrates a spine measurement system 100 in a non-limitingexample. The system 100 comprises a spinal instrument 102 that can becommunicatively coupled to a remote system 105. The spine measurementsystem 100 can further include alignment circuitry 103 to determinepositional information of at least one of an orientation, rotation,angle, and location. The positional information can relate to a tool,device, equipment, patient, or region of the muscular-skeletal system.In the example, alignment circuitry 103 can be part of spinal instrument102 or comprise external components. In one embodiment, externalcomponents comprising alignment circuitry 103 can couple to spinalinstrument 102 or to regions of the spine for determining positionalinformation. In one embodiment, location and position can be determinedvia one or more accelerometers. Alternatively, location and position canbe determined via a time of flight or differential time of flight of asignal. The positional information can include orientation andtranslation data used to assess an alignment of the spine 112. Thepositional information can be measured in real-time during the procedureor provided to remote system 105.

In the example, spinal instrument 102 can be used intra-operatively tomeasure a parameter of the spinal region. Spinal instrument 102 includesat least one sensor for measuring the parameter. Spinal instrument 102can have more than one sensor for measuring different parameters andproviding quantitative data to the surgeon in real-time. In oneembodiment, spinal instrument 102 measures load, position of load, andalignment. Spinal instrument 102 is not limited to load and alignmentmeasurement example. Other sensor types for measuring differentparameters can be integrated into the device. The quantitative datagenerated by spinal instrument 102 can be used to determine a locationfor placing a prosthetic component such as a pedicle screw or a spinecage in the spine. Spinal instrument 102 can be used to distract thespinal region being measured. In general, spinal instrument 102 andalignment circuitry 103 may be used within a sterile field 109 of anoperating room. The sterile field 109 can also be called a surgicalfield where a patient operation is performed. Typically, remote system105 is outside the sterile field 109 of the operating room. The remotesystem 105 can be a laptop, mobile workstation, display or other devicethat presents a Graphical User Interface (GUI) 107. In one embodiment,GUI 107 contains a workflow that shows the spine 112 and reports spinalinstrument quantitative measurement data. For example, remote system canreceive and display load, load position, and alignment data from spinalinstrument 102 and alignment circuitry 103. Alternatively, spinalinstrument 102 can have an interface for displaying or indicating thequantitative measurement data. In the example, the spinal instrument 102is a self-contained device for generating measurement data.

The GUI 107 is presented by way of the remote system 105 and spinemeasurement system 100. In the example, the GUI 107 may have more thanone window to show the quantitative measurement data provided by spinalinstrument 102 and alignment circuitry 103. GUI 107 is shown on thedisplay of remote system 105 for providing real-time quantitative datafrom spinal instrument 107 and alignment circuitry 103. In the example,spinal instrument 102 is being directed to a spinal region. Morespecifically, spinal instrument 102 is being directed between vertebraeof the spine. Sensors can be placed within a sensored head of spinalinstrument 102. The sensored head can be used to distract the vertebraethereby generating a gap between vertebrae that is the height of thesensored head. Spinal instrument 102 can be wired or wirelessly coupledto remote system 105. In the example, spinal instrument 102 iswirelessly coupled to remote system 105 for transmitting data. Thattransmitted data can include load, location, and position data. GUI 107can display alignment data in real-time such as shaft angle and arotation component corresponding to the direction of spinal instrument102 in relation to the vertebrae of interest. Furthermore, GUI 107 canprovide quantitative measurement data on the load and position of loadapplied by the vertebrae to the sensored head of spinal instrument 102after insertion. Thus, measurement system 100 allows the surgeon andmedical staff to visualize use of the spinal instrument 102 and thesensed parameters.

The spine measurement system 100 can be communicatively coupled to adatabase 123 system such as a server 125 to provide three-dimensional(3D) imaging (e.g., soft tissue) and 3D models (e.g., bone) capturedprior to, or during, surgery. The 3D imaging and models can be used inconjunction with positional information measured during the procedure toestablish relative location and orientation. The server 125 may be localin near vicinity or remotely accessed over the Internet 121. As oneexample, the server 125 provides 3D spine and vertebra models. A CATscanner (not shown) can be employed to produce a series ofcross-sectional x-ray images of a selected part of the body. A computeroperates the scanner, and the resulting picture represents a slice ofthe body. The server 125 produces a three-dimensional (3D) model fromthe slices. The server 125 can also provide 3D models generated fromMagnetic Resonance Imaging (MRI) scanners (not shown). The server 125may also support fluoroscopic imaging to provide real-time moving imagesof the internal structures of a patient with respect to the spinemeasurement system 100 devices through the use of X-ray source (notshown) and fluorescent screen.

In the example, the sensored head of spinal instrument 102 includes asensor for measuring load. In one embodiment, the sensored head includesmore than one sensor for measuring a location of an applied force,pressure, or load to the surfaces of the sensored head. Measuring thelocation of the applied force to surfaces of the sensored head of spinalinstrument 102 provides information related to the spinal region and thedistribution of the force. For example, an application may require aneven distribution of force applied over a large area of the surfaces ofthe sensored head. Conversely, an application may require a peak forceapplied over a small area of the surface of the sensored head. In eitherexample, spinal instrument 102 can provide measurement data related toforce magnitude and location of the applied force whereby the surgeonuses the quantitative data in conjunction with subjective informationfor assessing the probed spinal region.

Many physical parameters of interest within physical systems or bodiescan be measured by evaluating changes in the characteristics of energywaves or pulses. As one example, changes in the transit time or shape ofan energy wave or pulse propagating through a changing medium can bemeasured to determine the forces acting on the medium and causing thechanges. The propagation velocity of the energy waves or pulses in themedium can be affected by physical changes in of the medium. Thephysical parameter or parameters of interest can include, but are notlimited to, measurement of load, force, pressure, displacement, density,viscosity, and localized temperature. These parameters can be evaluatedby measuring changes in the propagation time of energy pulses or wavesrelative to orientation, alignment, direction, or position as well asmovement, rotation, or acceleration along an axis or combination of axesby wireless sensing modules or devices positioned on or within a body,instrument, equipment, or other mechanical system. Alternatively,measurements of interest can be taken using film sensors, mechanicalsensors, polymer sensors, mems devices, strain gauge, piezo-resistivestructure, and capacitive structures to name but a few.

FIG. 2 illustrates a spinal instrument 400 in a non-limiting example. Aside view and a top view are presented. Spinal instrument 400 is a moredetailed illustration of a non-limiting example of spinal instrument 102of FIG. 1. Spinal instrument 400 comprises a handle 409, a shaft 430,and a sensored head 407. The handle 409 is coupled at a proximal end ofthe shaft 430. Sensored head 407 is coupled to a distal end of the shaft430. A surgeon holds spinal instrument 400 by the handle 409 to directshaft 430 and sensored head 407 to a spinal region. In one embodiment,handle 409, shaft 430, and sensored head 407 form a rigid structure thathas little flex. Alternatively, one or more of handle 409, shaft 430,and sensored head 407 may have some flexibility. Spinal instrument 400includes an electronic assembly 401 operatively coupled to one or moresensors. The sensors can be coupled to surfaces 403/406 on movingcomponents 404/405 of sensored head 407. Electronic assembly 401 can belocated towards the proximal end of the shaft 407 or in handle 409. Asshown, the electronic assembly 401 is a module that is coupled to shaft409. Electronic assembly 401 comprises electronic circuitry thatincludes logic circuitry, an accelerometer, and communication circuitry.The electronic circuitry controls sensor measurement, receivesmeasurement data, stores the data, and can send the data to an externaldevice.

In one embodiment, surfaces 403 and 406 of sensored head 407 can have aconvex shape. The convex shape of surfaces 403 and 406 support placementof sensored head 407 within the spinal region and more specificallybetween the contours of vertebrae. In one embodiment, sensored head 407is height adjustable by way of the top component 404 and the bottomcomponent 405 through a jack 402 that evenly distracts and closesaccording to handle 409 turning motion 411. Jack 402 is coupled tointerior surfaces of components 404 and 405 of sensored head 407. Shaft430 includes one or more lengthwise passages. For example, interconnectsuch as a flexible wire interconnect can couple through one lengthwisepassage of shaft 430 such that electronic assembly 401 is operativelycoupled to one or more sensors in sensored head 407. Similarly, athreaded rod can couple through a second passage of shaft 430 forcoupling handle 409 to jack 404 thereby allowing height adjustment ofsensored head 407 via rotation of handle 409.

Spine instrument 400 can also determine location and orientation by wayof one or more embedded accelerometers. The sensored head 407 supportsmultiple functions that include the ability to determine a parameter ofthe procedure area (e.g., intervertebral space) including pressure,tension, shear, load, torque, bone density, and/or bearing weight. Inone embodiment, more than one load sensor can be included withinsensored head 407. The more than one load sensors can be coupled topredetermined locations of surfaces 403 and 406. Having more than oneload sensor allows the sensored head 407 to measure load magnitude andthe position of applied load to surfaces 403 and 406. The sensored head407 can be used to measure, adjust, and test a vertebral joint prior toinstalling a vertebral component. As will be seen ahead, measurementsystem 100 can evaluate the optimal insertion angle and position ofspinal instrument 400 during intervertebral load sensing. Themeasurement system 100 can replicate insertion angle and position forinstrument 400 or for another tool such as an insertion instrument.

In the present invention these parameters can be measured with anintegrated wireless sensored head 407 or device comprising an i)encapsulating structure that supports sensors and contacting surfacesand ii) an electronic assemblage that integrates a power supply, sensingelements, ultrasound resonator or resonators or transducer ortransducers and ultrasound waveguide or waveguides, biasing spring orsprings or other form of elastic members, an accelerometer, antennas andelectronic circuitry that processes measurement data as well as controlsall operations of energy conversion, propagation, and detection andwireless communications. Sensored head 407 or instrument 400 can bepositioned on or within, or engaged with, or attached or affixed to orwithin, a wide range of physical systems including, but not limited toinstruments, appliances, vehicles, equipments, or other physical systemsas well as animal and human bodies, for sensing and communicatingparameters of interest in real time.

Spinal instrument 400 can be used in the installation of a spinal cageas a non-limiting example. The spinal cage is used to space vertebrae inreplacement of a disc. The spinal cage is typically hollow and can beformed having external threads for fixation. Two or more cages are ofteninstalled between the vertebrae to provide sufficient support anddistribution of loading over the range of motion. In one embodiment, thespinal cage may be made of titanium for supporting spinal load andspacing between vertebrae. A bone growth material can also be placed inthe cage to initiate and promote bone growth thereby furtherstrengthening the intervertebral area long-term. Spinal instrument 400can be used to provide quantitative data such as load and position ofload for a region between vertebrae that may be a candidate for aprosthetic component such as the spinal cage. Typically, spinalinstrument 400 is inserted in a gap selected by the surgeon betweenvertebrae. Spinal instrument 400 measures load and position of load thatcan be viewed on an interface on the device or to a remote system suchas that disclosed in FIG. 1. The position of load corresponds to thevertebral area surfaces applying the load on surfaces 403 or 406 ofsensored head 407. The angle and position of insertion of the sensoredhead 407 of spinal instrument 400 can also be measured. The loadmagnitude and position of load measurement are used by the surgeon todetermine an implant location between the vertebrae and the size of thespinal cage for the implant location. Typically, the height and lengthof the selected spinal cage is approximately the height and length ofsensored head 407. Moreover, the area chosen for the spinal cagelocation may load the prosthetic component within a predetermined loadrange as measured by spinal instrument 400. Conversely, quantitativemeasurements of vertebral loading outside the predetermined range may befound unsuitable for prosthetic component installation. The surgeon canmodify the contact surfaces of the vertebrae to fall within thepredetermined range as measured by spinal instrument 400. The surgeoncan also locate a different region between the vertebrae that is moresuitable based on quantitative data provided by spinal instrument 400.

In the example, a spinal cage is inserted in the measured region afterremoving the sensored head 407. The spinal cage can be inserted in thesame location measured by sensored head 407 using quantitativemeasurement data. The alignment data of spinal instrument 400 isgenerated and recorded during an insertion process and measurement ofload and position of load. The loading on the implanted spinal cage wheninserted in the same position and angle as sensored head 407 isapproximately equal to the measurements made by spinal instrument 400.The recorded angle and position measurements can be subsequently used toguide the spinal cage into the same location and more specifically by asimilar insertion path as spinal instrument 400. In one embodiment,spinal instrument 400 can be used to place the prosthetic component intothe identified region. A separate instrument can also be used forinsertion of the prosthetic component.

FIG. 3 illustrates a spinal instrument 410 having integrated electronicsin a non-limiting example. Spinal instrument 410 is a more detailedillustration of a non-limiting example of spinal instrument 102 of FIG.1 and relates to spinal instrument 400. Electronic assembly 401 isplaced within handle 415 of spinal instrument 410. Placing electronicassembly 401 in handle 415 provides the benefit of isolating thecircuitry from the external environment. Handle 415 can further provideshock isolation for the electronic assembly 401 for reliability. In oneembodiment, an external wireless energy source 414 can be placed inproximity to a charging unit within electronic assembly 401 to initiatea wireless power recharging operation. The wireless energy source 414can include a power supply, a modulation circuit, and a data input. Thepower supply in energy source 414 can be a battery, a charging device, acapacitor, a power connection, or other energy source for generatingwireless power signals that can transfer power to spinal instrument 410.The external wireless energy source 414 can transmit energy in the formof, but not limited to, electromagnetic induction, or otherelectromagnetic or ultrasound emissions. In at least one exemplaryembodiment, the wireless energy source includes a coil toelectromagnetically couple and activate (e.g., power on) with aninduction coil in sensing device when placed in close proximity.

Electronic assembly 401 operatively couples to sensors in sensored head407 for measuring a parameter. Electronic assembly 401 includescommunication circuitry for transmitting measured parameter data to areceiver via data communications circuitry. The received parameter datacan be processed remotely to permit visualization of the level anddistribution of the parameter at various points on the sensored head.Information can also be provided to electronic assembly 401 usingexternal wireless energy source 414. Data can be provided through aninterface or port to external wireless energy source 414. Theinformation or data can be input from another data source, such as froma computer via a wired or wireless connection (e.g., USB, IEEE802.16,etc.). In one embodiment, external wireless energy source 414 includes amodulation circuitry that can modulate the input information onto thepower signals for sourcing energy to electronic assembly 401. In theexample, electronic assembly 401 has demodulation circuitry coupled forremoving and providing the information for use by spinal instrument 410from the power signals.

FIG. 4 illustrates an insert instrument 420 with vertebral components ina non-limiting example. Electronic assembly 401 as described hereinsupports the generation of orientation and position data of insertinstrument 420. In one embodiment, electronic assembly 401 includes anaccelerometer for providing orientation and position data. Referring toFIG. 11 briefly, electronic assembly 401 of insert instrument 420 canhave more or less circuitry than that disclosed for spinal instruments400 and 410. By way of measurement system 100, the user can replicatethe insertion angle, position and trajectory (path) to achieve proper orpre-planned placement of a vertebral component. Insert instrument 420comprises a handle 432, a shaft 434, and a tip 451. An attach/releasemechanism 455 couples to the proximal end of shaft 434 for controllingtip 451. Attach/release mechanism 455 allows a surgeon to retain orrelease vertebral components coupled to tip 451. Attach/releasemechanism 455 can mechanically couple through shaft 434 to control tip451. Alternatively, attach/release mechanism 455 can be an electroniccontrol. In the example, handle 432 extends at an angle in proximity toa proximal end of shaft 434. Positioning of handle 432 allows thesurgeon to accurately direct tip 451 in a spinal region while allowingaccess to attach/release mechanism 455. Electronic assembly can behoused in handle 432 or attached to insert instrument 420. Referring toFIG. 12 briefly, electronic assembly 401 includes communicationcircuitry to securely transmit and receive data from a remote system.Insert instrument 420 is a tool of spine measurement system 100.Quantitative measurement data such as orientation and position data canbe transmitted to remote system 105 of FIG. 1 for real time andvisualization of an insertion process. Electronic assembly 401 can alsocouple to one or more sensors of insert instrument 420. In a firstexample, tip 451 can be coupled to a pressure sensor to determine aforce, pressure, or load being applied by the spinal region to aprosthetic component coupled thereto. In a second example, tip 451 canbe removable such that a sensored head can be coupled to insertinstrument 420. In a third example, the prosthetic component can includea sensor. The sensor of the prosthetic component includes an interfacethat couples to electronic assembly 401 for providing quantitativemeasurement data.

In the illustration, an example prosthetic component is a spine cage475. Spine cage 475 is a small hollow device, usually made of titanium,with perforated walls that can be inserted between the vertebrae of thespine during a surgery. In general, a distraction process spaces thevertebrae to a predetermined distance prior insertion of spine cage 475.Spine cage 475 can increase stability, decrease vertebral compression,and reduce nerve impingement as a solution to improve patient comfort.Spine cage 475 can include surface threads that allow the cage to beself-tapping and provide further stability. Spine cage 475 can be porousto include bone graft material that supports bone growth betweenvertebral bodies through cage 475. More than one spine cage can beplaced between vertebrae to alleviate discomfort. Proper placement andpositioning of spine cage 475 is important for successful long-termimplantation and patient outcome. As mentioned above, the orientationand position of insert instrument 420 can be tracked in real-time inrelation to the spinal region of interest. In one embodiment, theorientation and position being tracked is a prosthetic componentretained by insert instrument 420. In the example, the prostheticcomponent is spine cage 475. Spine cage 475 can be tracked in 3D spacebecause the location of the prosthetic component is known in relation tothe spinal instrument 420 and the one or more measurement accelerometerstherein.

In the illustration a second prosthetic component is a pedicle screw478. The pedicle screw 478 is a particular type of bone screw designedfor implantation into a vertebral pedicle. There are two pedicles pervertebra that couple to other structures (e.g. lamina, vertebral arch).A polyaxial pedicle screw may be made of titanium to resist corrosionand increase component strength. The pedicle screw length ranges from 30mm to 60 mm. The diameter ranges from 5.0 mm to 8.5 mm. It is notlimited to these dimensions, which serve as dimensional examples.Pedicle screw 478 can be used in instrumentation procedures to affixrods and plates to the spine to correct deformity, and/or treat trauma.It can be used to immobilize part of the spine to assist fusion byholding bony structures together. By way of electronic assembly 401(which may be internally or externally integrated), the insertinstrument 420 can determine depth and angle for screw placement andguide the screw therein. In the example, one or more accelerometers areused to provide orientation, rotation, angle, or position information oftip 451 during an insertion process.

In one arrangement, the screw 478 is embedded with sensors. The sensorscan transmit energy and obtain a density reading and monitor the changein density over time. As one example, the measurement system 100 canmonitor and report healing of a fracture site. The sensors can detectthe change in motion at the fracture site as well as the motion betweenthe screw and bone. Such information aids in monitoring healing andgives the healthcare provider an ability to monitor vertebral weightbearing as indicated. The sensors can also be activated externally tosend energy waves to the fracture itself to aid in healing.

FIG. 5 illustrates a lateral view of spinal instrument 400 positionedbetween vertebrae of the spine for sensing vertebral parameters in anon-limiting example. The illustration can also apply to spinalinstrument 410 and insert instrument 420. In general, a compressiveforce is applied to surfaces 403 and 406 when sensored head 407 isinserted into the spinal region. In one embodiment, sensored head 407includes two or more load sensors that identify magnitude vectors ofloading on surface 403, surface 406, or both associated withinter-vertebral force there between. In the example shown, the spinalinstrument 400 is positioned between vertebra (L5) and the Sacrum (S1)such that a compressive force is applied to surfaces 403 and 406. Oneapproach for inserting the instrument 400 is from the posterior (backside) through a minilaparotomy as an endoscopic approach may bedifficult to visualize or provide good exposure. Another approach isfrom the anterior (front side) which allows the surgeon to work throughthe abdomen to reach the spine. In this way spine muscles located in theback are not damaged or cut; avoiding muscle weakness and scarring.Spinal instrument 400 can be used with either the anterior or posteriorspine approach.

Aspects of the sensorized components of the spine instrument 400 aredisclosed in U.S. patent application Ser. No. 12/825,638 entitled“System and Method for Orthopedic Load Sensing Insert Device” filed Jun.29, 2010, and U.S. patent application Ser. No. 12/825,724 entitled“Wireless Sensing Module for Sensing a Parameter of theMuscular-Skeletal System” filed Jun. 29, 2010 the entire contents ofwhich are hereby incorporated by reference. Briefly, the sensored head407 can measure forces (Fx, Fy, and Fz) with corresponding locations andtorques (e.g. Tx, Ty, and Tz) and edge loading of vertebrae. Theelectronic circuitry 401 (not shown) controls operation and measurementsof the sensors in sensored head 407. The electronic circuitry 401further includes communication circuitry for short-range datatransmission. It can then transmit the measured data to the remotesystem to provide real-time visualization for assisting the surgeon inidentifying any adjustments needed to achieve optimal joint balancing.

A method of installing a component in the muscular-skeletal system isdisclosed below. The steps of the method can be performed in any order.An example of placing a cage between vertebrae is used to demonstratethe method but the method is applicable to other muscular-skeletalregions such as the knee, hip, ankle, spine, shoulder, hand, arm, andfoot. In a first step, a sensored head of a predetermined width isplaced in a region of the muscular-skeletal system. In the example, theinsertion region is between vertebrae of the spine. A hammer can be usedto tap an end of the handle to provide sufficient force to insert thesensored head between the vertebrae. The insertion process can alsodistract the vertebrae thereby increasing a separation distance. In asecond step, the position of the load applied to the sensored head ismeasured. Thus, the load magnitude and the position of the loading onthe surfaces of the sensored head are available. How the load applied bythe muscular-skeletal system is positioned on the surfaces of thesensored head can aid in determining stability of the component onceinserted. An irregular loading applied to sensored head can predict ascenario where the applied forces thrust the component away from theinserted position. In general, the sensored head is used to identify asuitable location for insertion of the component based on quantitativedata. In a third step, the load and position of load data from thesensored head is displayed on a remote system in real-time. Similarly,in a fourth step, the at least one of orientation, rotation, angle, orposition is displayed on the remote system in real-time. Changes made inpositioning the sensored head are reflected in data on the remote systemdisplay. In a fifth step, a location between vertebrae havingappropriate loading and position is identified and the correspondingquantitative measurement data is stored in memory.

In a sixth step, the sensored head is removed. In a seventh step, thecomponent is inserted in the muscular-skeletal system. As an example,the stored quantitative measurement data is used to support thepositioning of the component in the muscular-skeletal system. In theexample, the insertion instrument can be used to direct the componentinto the muscular-skeletal system. The insertion instrument is an activedevice providing orientation, rotation, angle, or position of thecomponent as it is being inserted. The previously measured direction andlocation of the insertion of the sensored head can be used to guide theinsertion instrument. In one embodiment, the remote system display canaid in displaying relational alignment of the insertion instrument andcomponent to the previously inserted sensored head. The insertioninstrument in conjunction with the system can provide visual, vocal,haptic or other feedback to further aid in directing the placement ofthe component. In general, the component being inserted hassubstantially equal height and length as the sensored head. Ideally, thecomponent is inserted identical in location and position to thepreviously inserted sensored head such that the loading and position ofload on the component is similar to the quantitative measurements. In aneighth step, the component is positioned identically to the previouslyinserted sensored head and released. The insertion instrument can thenbe removed from the muscular-skeletal system. In a ninth step, at leastthe sensored head is disposed of.

Thus, the sensored head is used to identify a suitable location forinsertion of the component. The insertion is supported by quantitativemeasurements that include position and location. Furthermore, theapproximate loading and position of loading on the component is knownafter the procedure has been completed. In general, knowing the loadapplied by the muscular-skeletal system and the position on the surfacesof the component can aid in determining stability of the componentlong-term. An irregular loading applied on the component can result inthe applied forces thrusting the component away from the insertedposition.

FIG. 6 illustrates a graphical user interface (GUI) 500 showing a axial(top) view of the sensorized spinal instrument of FIG. 5 in anon-limiting example. The graphical user interface 500 is presented byway of the remote system 105 and spine measurement system 100 of FIG. 1.Reference is made to spinal instrument 400 of FIG. 2 and measurementsystem 100 of FIG. 1. The GUI 500 illustrates an example of how data canbe presented. The GUI 500 includes a window 510 and a related window520. The window 520 shows the spine instrument 400 and sensor head 407in relation to vertebrae 522 under evaluation. In this example, a axial(top) view of the vertebra is shown. It indicates a shaft angle 523 anda rotation component 524 which reveal the approach angle and rotation ofthe spine instrument 400, for instance, as it is moved forward into theincision. The window 520 and corresponding GUI information is presentedand updated in real-time during the procedure. It permits the surgeon tovisualize use of spinal instrument 400 and the sensed parameters. Thewindow 510 shows a sensing surface (403 or 406) of the sensored head407. A cross hair 512 is superimposed on the sensor head image toidentify the maximal point of force and location. It can also lengthento show vertebral edge loading. A window 513 reports the load force, forexample, 20 lbs across the sensor head surface. This information ispresented and updated in real-time during the procedure.

As previously noted, spine measurement system 100 can be usedintra-operatively to aid in the implantation of the prosthesis,instrumentation, and hardware by way of parameter sensing (e.g.,vertebral load, edge loading, compression, etc.). The spinal instrument400 can include a power source that can provide power for only a singleuse or procedure. In one embodiment, components such as spinalinstrument 400 can be disposed of after being used in a procedure. Theremote system 105 can be placed outside the surgical field for use indifferent procedures and with different tools.

In the spine, the affects on the bony and soft tissue elements areevaluated by the measurement system 100, as well as the soft tissue(e.g., cartilage, tendon, ligament) changes during surgery, includingcorrective spine surgery. The sensors of a tool, device, or implant usedduring the operation (and post-operatively) can support the evaluationand visualization of changes over time and report dynamic changes. Thesensors can be activated intra-operatively when surgical parameterreadings are stored. Immediately post-operatively, the sensor isactivated and a baseline is known.

The measurement system 100 allows evaluation of the spine and connectivetissue regarding, but not limited to bone density, fluid viscosity,temperature, strain, pressure, angular deformity, vibration, load,torque, distance, tilt, shape, elasticity, and motion. Because thesensors span a vertebral space, they can predict changes in thevertebral component function prior to their insertion. As previouslynoted, the measurement system 100 can be used to place spine instrument400 in the inter-vertebral space, where it is shown positioned relativeto the vertebral body 522. Once it is placed and visually confirmed inthe vertebral center, the system 100 reports any edge loading on theinstrument which in turn is used to size a proper vertebral device andinsertion plan (e.g., approach angle, rotation, depth, path trajectory).Examples of implant component function include bearing wear, subsidence,bone integration, normal and abnormal motion, heat, change in viscosity,particulate matter, kinematics, to name a few.

FIG. 7 illustrates spinal instrument 400 positioned between vertebra ofthe spine for intervertebral position and force sensing in accordancewith an example embodiment. Reference is made to spinal instrument 400of FIG. 2 and measurement system 100 of FIG. 1. The illustration canalso apply to spinal instrument 410 of FIG. 3 and insert instrument 420of FIG. 4. As shown, sensored head 407 of spinal instrument 400 isplaced between vertebrae L3 and vertebrae L4. The spinal instrument 400distracts the L3 and L4 vertebrae the height of sensored head 407 andprovides quantitative data on load magnitude and position of load. Asmentioned previously, the spine measurement system 100 can includealignment circuitry 103. The alignment circuitry 103 can compriseexternal devices such as a wand 510 and a wand 520. Wands 510 and 520can include accelerometers or circuitry to generate signals for time offlight and differential time of flight measurements. Wands 510 and 520are coupled to different areas of the spinal region. In one embodiment,spinal instrument 400 includes circuitry that communicates with wand 510and a wand 520 to determine position and alignment. Wands 510 and 520are coupled to different vertebra of the spine with spinal instrument400 positioned to be in line of sight with each wand. A long shaft 514is provided on each wand to permit placement within vertebra of thespine and also line up with other wands and an electronic assembly 401of the spine instrument 400. Wand 510 tracks an orientation and positionof vertebra L3, while wand 520 tracks an orientation and position ofvertebra L4. This permits the spine measurement system 100 to track anorientation and movement of the spine instrument 400 relative tomovement of the neighboring vertebra. Each wand can also be sensorizedsimilar to spinal instrument 400. Wands 510 and wand 520 respectivelyincludes a sensor 512 and a sensor 513. Sensors 512 and 513 can transmitand receive positional information. In the example, electronic assembly401 in conjunction with wands 510 and 520 dually serves to resolve anorientation and position of spinal instrument 400 during the procedure.Thus, spine measurement system 100 can simultaneously providequantitative measurement data such as load and position of load,position and alignment of spinal instrument 400, and position andalignment of one or more regions of the spine.

FIG. 8 illustrates user interface 600 showing the spinal instrument 400of FIG. 7 in accordance with an example embodiment. Reference is made tospinal instrument 400 of FIG. 2 and measurement system 100 of FIG. 1.The illustration can also apply to spinal instrument 410 of FIG. 3 andinsert instrument 420 of FIG. 4. User interface 600 is presented by wayof the remote system 105 and spine measurement system 100 (see FIG. 1).The GUI 600 includes a window 610 and a related window 620. The window620 shows spinal instrument 400 and sensored head 407 in relation to avertebral component 622 under evaluation. In this example, a sagitalview of the spine column is shown. It indicates a shaft angle 623 and arotation component 624 which reveal the approach angle and rotation ofspinal instrument 400 and sensored head 407. The window 620 andcorresponding GUI information is presented and updated in real-timeduring the procedure. It permits the surgeon to visualize sensored head407 of the spinal instrument 400 and the sensed load force parameters.The window 610 shows sensing surfaces of the sensor head 407. A crosshair 612 is superimposed on the image of sensored head 407 to identifythe maximal point of force and location. It can also adjust in width andlength to show vertebral edge loading. Another GUI window 613 reportsthe load force across the sensored head 407 surface. The GUI 600 ispresented and updated in real-time during the procedure.

FIG. 9 illustrates a lateral view of spinal insert instrument 420 forplacement of spine cage 475 in accordance with an example embodiment.The illustration can also apply to spinal instrument 400 of FIG. 2 andspinal instrument 410 of FIG. 3 when adapted to retain components forinsert installation. Insert instrument 420 provides a surgical means forimplanting vertebral component 475 (e.g. spine cage, pedicle screw,sensor) between the L3 and L4 vertebrae in the illustration. Mechanicalassembly tip 451 at the distal end of shaft 434 permits attaching andreleasing of the vertebral component by way of attach/release mechanism455. The vertebral component 475 can be placed in the back of the spinethrough a midline incision in the back, for example, via posteriorlumbar interbody fusion (PLIF) as shown. The insert instrument 420 cansimilarly be used in anterior lumbar interbody fusion (ALIF) procedures.

In one method herein contemplated, the position of spine cage 475 priorto insertion is optimally defined for example, via 3D imaging or viaultrasonic navigation as described with alignment circuitry 103 of FIG.1 with spinal instrument 400 shown in FIGS. 6 and 7. The load sensor 407(see FIG. 7) is positioned between the vertebra to assess loading forcesas described above where an optimal insertion path and trajectory istherein defined. The load forces and path of instrument insertion arerecorded. Thereafter as shown in FIG. 9, insert instrument 420 insertsthe final spinal cage 475 according to the recorded path of spinalinstrument 400 and as based on the load forces. During the insertion,the GUI as shown in FIG. 10 navigates the spinal instrument 420 to therecorded insertion point. Spinal insert instrument 420 can be equippedwith one or more load sensors serving as a placeholder to a final spinalcage. After placement of spinal cage 475 between the vertebra, releaseof the spine cage from insert instrument 420, and removal of the insertinstrument 420, the open space occupied around the spinal cage is thenclosed down via rods and pedicle screws on the neighboring vertebra.This compresses the surrounding vertebra onto the spinal cage, andprovides stability for verterbral fusion. During this procedure, the GUI700 of FIG. 10 reports change in spinal anatomy, for example, Lordosisand Kyphosis, due to adjustment of the rods and tightening of thepedicle screws. Notably, the GUI 700 also provides visual feedbackindicating which the amount and directions to achieve the planned spinalalignment by way of instrumented adjustments to the rods and screws.

FIG. 10 illustrates graphical user interface (GUI) 700 showing a lateralview of the insert instrument 420 of FIG. 9 in a non-limiting example.GUI 700 can be presented by way of the remote system 105 and measurementsystem 100 of FIG. 1. GUI 700 includes a window 710 and a related window720. The window 720 shows insert instrument 420 and vertebral component475 in relation to the L4 and L5 vertebrae under evaluation. In thisexample, a sagital (side) view of the spine column is shown. Itindicates a shaft angle 723 and a rotation component 724 which revealthe approach angle and rotation of insert instrument 420 and vertebralcomponent 475. Window 720 and corresponding GUI information can bepresented and updated in real-time during the procedure. The real-timedisplay permits the surgeon to visualize the vertebral component 475 ofthe insert instrument 420 according to the previously sensed load forceparameters.

Window 710 shows a target sensored head orientation 722 and a currentinstrument head orientation 767. The target orientation 722 shows theapproach angle, rotation and trajectory path previously determined whenthe spine instrument 400 was used for evaluating loading parameters. Thecurrent instrument head orientation 767 shows tracking of the insertinstrument 420 currently used to insert the spine cage 475. GUI 700presents the target orientation model 722 in view of the currentinstrument head orientation 767 to provide visualization of thepreviously determined surgical plan.

Referring to FIGS. 1, 5, 6, 7, and 8, spinal instrument 400 is used toassess procedural parameters (e.g., angle, rotation, path) in view ofdetermined sensing parameters (e.g., load, force, edge). Referring backto FIG. 10, once these procedural parameters were determined,measurement system 100 by way of GUI 700 now guides the surgeon withinsert instrument 420 to insert the vertebral components 475 (e.g.,spine cage, pedicle screw). In one arrangement, measurement system 100provides haptic feedback to guide insert instrument 420 during theinsertion procedure. For example, insert instrument 420 can vibrate whenthe current approach angle 713 deviates from the target approach angle,provides a visual cue (red/green indication), or when the orientation767 is not aligned with the target trajectory path 722. The amount offeedback (e.g. haptic or visual) can correspond to the amount ofdeviation. Alternatively, vocal feedback can be provided by system 100to supplement the visual and haptic information being provided. The GUI700 effectively recreates the position and target path of insertinstrument 420 through visual and haptic feedback based on the previousinstrumenting. It is contemplated herein that spinal instrument 420 canalso be adapted for both load measurement and an insertion process.

The loading, balance, and position can be adjusted during surgery withinpredetermined quantitatively measured ranges through surgical techniquesand adjustments using data from sensorized devices disclosed herein foralignment and parameter through measurement system 100. Both the trialand final inserts (e.g., spine cage, pedicle screw, sensors, etc.) caninclude the sensing module to provide measured data to the remote systemfor display. A final insert can also be used to monitor the vertebraljoint long term. The data can be used by the patient and health careproviders to ensure that the vertebral joint or fused vertebrae isfunctioning properly during rehabilitation and as the patient returns toan active normal lifestyle. Conversely, the patient or health careprovider can be notified when the measured parameters are out ofspecification. This provides early detection of a spine problem that canbe resolved with minimal stress to the patient. The data from finalinsert can be displayed on a screen in real time using data from theembedded sensing module. In one embodiment, a handheld device is used toreceive data from final insert. The handheld device can be held inproximity to the spine allowing a strong signal to be obtained forreception of the data.

A method is disclosed for inserting a prosthetic component in a spinalregion in a non-limiting example. The method can be practiced with moreor less than the number of steps shown and is not limited to the ordershown. To describe the method, reference will be made to FIGS. 1, 7, and9 although it is understood that the method can be implemented in anyother manner using other suitable components. In a first step, thespinal region is distracted to create a gap or spacing. The distractionprocess produces a suitable spacing for receiving a prostheticcomponent. As disclosed herein, the distraction process can alsogenerate quantitative data such as load and position of loadmeasurements applied by the spinal region to a measurement device ofsimilar size to the prosthetic component. In a second step, theprosthetic component is directed to the spinal region. In the example,an insert instrument is used by a surgeon to direct the prostheticcomponent held by the tool at a tip of the device. In a third step, theinsert instrument measures at least one of orientation, rotation, angle,or position of the prosthetic component. The insert instrument can tracka trajectory of the insert instrument and prosthetic component inreal-time during the insertion process. In a fourth step, the insertinstrument transmits data related to one of orientation, rotation,angle, or position of the prosthetic component and insert instrument. Inthe example, the data is transmitted wirelessly local to the procedure.

In a fifth step, the transmitted data from the insert instrument isdisplayed on a remote system. In the example, the remote system can bein the operating room where the procedure is being performed in view ofthe surgeon. The at least one of orientation, rotation, angle, orposition measurement data can be displayed in a manner that allowsvisualization of the trajectory of the prosthetic component to thespinal region. The visualization allows the surgeon to better direct theprosthetic component where visibility to the region is limited.Furthermore, the visualization provides the benefit of placing theprosthetic component in a previously identified area and at a similartrajectory of the spinal region using quantitative measurement data. Ina sixth step, the trajectory of the insert instrument and prostheticcomponent being tracked can be compared with a trajectory previouslymeasured. The compared trajectories can be displayed and visualized onthe display of the remote system.

In a seventh step, the prosthetic component is inserted into the spinalregion. In the example, the prosthetic component is placed in the gap orspacing from the prior distraction process. The prosthetic component canbe placed in approximately the same location and alignment of a priordevice such as the spinal instrument disclosed herein. In an eighthstep, the prosthetic component is released in the spinal region. Thesurgeon can view the placement of the prosthetic component on the remotedisplay. The location and alignment of the prosthetic component issupported by the measurement data provided by the insert instrument. Theattach/release mechanism is used to release the prosthetic componentfrom the insert instrument. In a ninth step, the insert instrument isremoved from the spinal region. In a tenth step, the insert instrumentcan be disposed of after the procedure is completed. Alternatively, theinsert instrument can be sterilized for use in another procedure.

FIG. 11 is a block diagram of the components of spinal instrument 400 inaccordance with an example embodiment. The block diagram can also applyto spinal instrument 410 of FIG. 3 and insert instrument 420 of FIG. 4.It should be noted that spinal instrument 400 could comprise more orless than the number of components shown. Spinal instrument 400 is aself-contained tool that can measure a parameter of themuscular-skeletal system. In the example, the spinal instrument 400measures load and position of load when inserted in a spinal region. Theactive components of spinal instrument 400 include one or more sensors1602, a load plate 1606, a power source 1608, electronic circuitry 1610,a transceiver 1612, and an accelerometer 1614. In a non-limitingexample, an applied compressive force is applied to sensors 1602 by thespinal region and measured by the spinal instrument 400.

The sensors 1602 can be positioned, engaged, attached, or affixed to thesurfaces 403 and 406 of spinal instrument 400. In general, a compressiveforce is applied by the spinal region to surfaces 403 and 406 wheninserted therein. The surfaces 403 and 406 couple to sensors 1602 suchthat a compressive force is applied to each sensor. In one embodiment,the position of applied load to surfaces 403 and 406 can be measured. Inthe example, three load sensors are used in the sensored head toidentify position of applied load. Each load sensor is coupled to apredetermined position on the load plate 1606. The load plate 1606couples to surface 403 to distribute a compressive force applied to thesensored head of spinal instrument 400 to each sensor. The load plate1606 can be rigid and does not flex when distributing the force,pressure, or load to sensors 1602. The force or load magnitude measuredby each sensor can be correlated back to a location of applied load onthe surface 403.

In the example of intervertebral measurement, the sensored head havingsurfaces 403 and 406 can be positioned between the vertebrae of thespine. Surface 403 of the sensored head couples to a first vertebralsurface and similarly the surface 406 couples to a second vertebralsurface. Accelerometer 1614 or an external alignment system can be usedto measure position and orientation of the sensored head as it isdirected into the spinal region. The sensors 1602 couple to theelectronic circuitry 1610. The electronic circuitry 1610 comprises logiccircuitry, input/output circuitry, clock circuitry, D/A, and A/Dcircuitry. In one embodiment, the electronic circuitry 1610 comprises anapplication specific integrated circuit that reduces form factor, lowerspower, and increases performance. In general, the electronic circuitry1610 controls a measurement process, receives the measurement signals,converts the measurement signals to a digital form, supports display onan interface, and initiates data transfer of measurement data.Electronic circuitry 1610 measures physical changes in the sensors 1602to determine parameters of interest, for example a level, distributionand direction of forces acting on the surfaces 403 and 406. The insertsensing device 400 can be powered by an internal power source 1608.Thus, all the components required to measure parameters of themuscular-skeletal system reside in the spinal instrument 400.

As one example, sensors 1602 can comprise an elastic or compressiblepropagation structure between a first transducer and a secondtransducer. The transducers can be an ultrasound (or ultrasonic)resonator, and the elastic or compressible propagation structure can bean ultrasound waveguide. The electronic circuitry 1610 is electricallycoupled to the transducers to translate changes in the length (orcompression or extension) of the compressible propagation structure toparameters of interest, such as force. The system measures a change inthe length of the compressible propagation structure (e.g., waveguide)responsive to an applied force and converts this change into electricalsignals, which can be transmitted via the transceiver 1612 to convey alevel and a direction of the applied force. For example, thecompressible propagation structure has known and repeatablecharacteristics of the applied force versus the length of the waveguide.Precise measurement of the length of the waveguide using ultrasonicsignals can be converted to a force using the known characteristics.

Sensors 1602 are not limited to waveguide measurements of force,pressure, or load sensing. In yet other arrangements, sensors 1602 caninclude piezo-resistive, compressible polymers, capacitive, optical,mems, strain gauge, chemical, temperature, pH, and mechanical sensorsfor measuring parameters of the muscular-skeletal system. In analternate embodiment, a piezo-resistive film sensor can be used forsensing load. The piezo-resistive film has a low profile therebyreducing the form factor required for the implementation. Thepiezo-resistive film changes resistance with applied pressure. A voltageor current can be applied to the piezo-resistive film to monitor changesin resistance. Electronic circuitry 1610 can be coupled to apply thevoltage or current. Similarly, electronic circuitry 1610 can be coupledto measure the voltage and current corresponding to a resistance of thepiezo-resistive film. The relation of piezo-resistive film resistance toan applied force, pressure, or load is known. Electronic circuitry 1610can convert the measured voltage or current to a force, pressure, orload applied to the sensored head. Furthermore, electronic circuitry1610 can convert the measurement to a digital format for display ortransfer for real-time use or for being stored. Electronic circuitry1610 can include converters, inputs, outputs, and input/outputs thatallow serial and parallel data transfer whereby measurements andtransmission of data can occur simultaneously. In one embodiment, anASIC is included in electronic circuitry 1610 that incorporates digitalcontrol logic to manage control functions and the measurement process ofspinal instrument 400 as directed by the user.

The accelerometer 1614 can measure acceleration and static gravitationalpull. Accelerometer 1614 can be single-axis and multi-axis accelerometerstructures that detect magnitude and direction of the acceleration as avector quantity. Accelerometer 1614 can also be used to senseorientation, vibration, impact and shock. The electronic circuitry 1610in conjunction with the accelerometer 1614 and sensors 1602 can measureparameters of interest (e.g., distributions of load, force, pressure,displacement, movement, rotation, torque, location, and acceleration)relative to orientations of spinal instrument 400. In such anarrangement, spatial distributions of the measured parameters relativeto a chosen frame of reference can be computed and presented forreal-time display.

The transceiver 1612 comprises a transmitter 1622 and an antenna 1620 topermit wireless operation and telemetry functions. In variousembodiments, the antenna 1620 can be configured by design as anintegrated loop antenna. The integrated loop antenna is configured atvarious layers and locations on a printed circuit board having otherelectrical components mounted thereto. For example, electronic circuitry1610, power source 1608, transceiver 1612, and accelerometer 1614 can bemounted on a circuit board that is located on or in spinal instrument400. Once initiated the transceiver 1612 can broadcast the parameters ofinterest in real-time. The telemetry data can be received and decodedwith various receivers, or with a custom receiver. The wirelessoperation can eliminate distortion of, or limitations on, measurementscaused by the potential for physical interference by, or limitationsimposed by, wiring and cables coupling the sensing module with a powersource or with associated data collection, storage, display equipment,and data processing equipment.

The transceiver 1612 receives power from the power source 1608 and canoperate at low power over various radio frequencies by way of efficientpower management schemes, for example, incorporated within theelectronic circuitry 1610 or the application specific integratedcircuit. As one example, the transceiver 1612 can transmit data atselected frequencies in a chosen mode of emission by way of the antenna1620. The selected frequencies can include, but are not limited to, ISMbands recognized in International Telecommunication Union regions 1, 2and 3. A chosen mode of emission can be, but is not limited to, GaussianFrequency Shift Keying, (GFSK), Amplitude Shift Keying (ASK), PhaseShift Keying (PSK), Minimum Shift Keying (MSK), Frequency Modulation(FM), Amplitude Modulation (AM), or other versions of frequency oramplitude modulation (e.g., binary, coherent, quadrature, etc.).

The antenna 1620 can be integrated with components of the sensing moduleto provide the radio frequency transmission. The antenna 1620 andelectronic circuitry 1610 are mounted and coupled to form a circuitusing wire traces on a printed circuit board. The antenna 1620 canfurther include a matching network for efficient transfer of the signal.This level of integration of the antenna and electronics enablesreductions in the size and cost of wireless equipment. Potentialapplications may include, but are not limited to any type of short-rangehandheld, wearable, or other portable communication equipment wherecompact antennas are commonly used. This includes disposable modules ordevices as well as reusable modules or devices and modules or devicesfor long-term use.

The power source 1608 provides power to electronic components of thespinal instrument 400. In one embodiment, power source 1608 can becharged by wired energy transfer, short-distance wireless energytransfer or a combination thereof. External power sources for providingwireless energy to power source 1608 can include, but are not limitedto, a battery or batteries, an alternating current power supply, a radiofrequency receiver, an electromagnetic induction coil, a photoelectriccell or cells, a thermocouple or thermocouples, or an ultrasoundtransducer or transducers. By way of power source 1608, spinalinstrument 400 can be operated with a single charge until the internalenergy is drained. It can be recharged periodically to enable continuousoperation. The power source 1608 can further utilize power managementtechniques for efficiently supplying and providing energy to thecomponents of spinal instrument 400 to facilitate measurement andwireless operation. Power management circuitry can be incorporated onthe ASIC to manage both the ASIC power consumption as well as othercomponents of the system.

The power source 1608 minimizes additional sources of energy radiationrequired to power the sensing module during measurement operations. Inone embodiment, as illustrated, the energy storage 1608 can include acapacitive energy storage device 1624 and an induction coil 1626. Theexternal source of charging power can be coupled wirelessly to thecapacitive energy storage device 1624 through the electromagneticinduction coil or coils 1626 by way of inductive charging. The chargingoperation can be controlled by a power management system designed into,or with, the electronic circuitry 1610. For example, during operation ofelectronic circuitry 1610, power can be transferred from capacitiveenergy storage device 1624 by way of efficient step-up and step-downvoltage conversion circuitry. This conserves operating power of circuitblocks at a minimum voltage level to support the required level ofperformance. Alternatively, power source 1608 can comprise one or morebatteries that are housed within spinal instrument 400. The batteriescan power a single use of the spinal instrument 400 whereby the deviceis disposed after it has been used in a surgery.

In one configuration, the external power source can further serve tocommunicate downlink data to the transceiver 1612 during a rechargingoperation. For instance, downlink control data can be modulated onto thewireless energy source signal and thereafter demodulated from theinduction coil 1626 by way of electronic circuitry 1610. This can serveas a more efficient way for receiving downlink data instead ofconfiguring the transceiver 1612 for both uplink and downlink operation.As one example, downlink data can include updated control parametersthat the spinal instrument 400 uses when making a measurement, such asexternal positional information, or for recalibration purposes. It canalso be used to download a serial number or other identification data.

The electronic circuitry 1610 manages and controls various operations ofthe components of the sensing module, such as sensing, power management,telemetry, and acceleration sensing. It can include analog circuits,digital circuits, integrated circuits, discrete components, or anycombination thereof. In one arrangement, it can be partitioned amongintegrated circuits and discrete components to minimize powerconsumption without compromising performance. Partitioning functionsbetween digital and analog circuit enhances design flexibility andfacilitates minimizing power consumption without sacrificingfunctionality or performance. Accordingly, the electronic circuitry 1610can comprise one or more integrated circuits or ASICs, for example,specific to a core signal-processing algorithm.

In another arrangement, the electronic circuitry 1610 can comprise acontroller such as a programmable processor, a Digital Signal Processor(DSP), a microcontroller, or a microprocessor, with associated storagememory and logic. The controller can utilize computing technologies withassociated storage memory such a Flash, ROM, RAM, SRAM, DRAM or otherlike technologies for controlling operations of the aforementionedcomponents of the sensing module. In one arrangement, the storage memorymay store one or more sets of instructions (e.g., software) embodyingany one or more of the methodologies or functions described herein. Theinstructions may also reside, completely or at least partially, withinother memory, and/or a processor during execution thereof by anotherprocessor or computer system.

The electronics assemblage also supports testability and calibrationfeatures that assure the quality, accuracy, and reliability of thecompleted wireless sensing module or device. A temporary bi-directionalcoupling can be used to assure a high level of electrical observabilityand controllability of the electronics. The test interconnect alsoprovides a high level of electrical observability of the sensingsubsystem, including the transducers, waveguides, and mechanical springor elastic assembly. Carriers or fixtures emulate the final enclosure ofthe completed wireless sensing module or device during manufacturingprocessing thus enabling capture of accurate calibration data for thecalibrated parameters of the finished wireless sensing module or device.These calibration parameters are stored within the on-board memoryintegrated into the electronics assemblage.

Applications for the electronic assembly comprising the sensors 1602 andelectronic circuitry 1610 may include, but are not limited to,disposable modules or devices as well as reusable modules or devices andmodules or devices for long-term use. In addition to non-medicalapplications, examples of a wide range of potential medical applicationsmay include, but are not limited to, implantable devices, modules withinimplantable devices, intra-operative implants or modules withinintra-operative implants or trial inserts, modules within inserted oringested devices, modules within wearable devices, modules withinhandheld devices, modules within instruments, appliances, equipment, oraccessories of all of these, or disposables within implants, trialinserts, inserted or ingested devices, wearable devices, handhelddevices, instruments, appliances, equipment, or accessories to thesedevices, instruments, appliances, or equipment.

FIG. 12 is a diagram of an exemplary communications system 1700 forshort-range telemetry in accordance with an exemplary embodiment. Theillustration applies to spinal instrument 400 of FIG. 2, spinalinstrument 410 of FIG. 3, insert instrument 420 of FIG. 4, and spinemeasurement system 100 of FIG. 1. It should be noted that communicationsystem 1700 may comprise more or less than the number of componentsshown. As illustrated, the communications system 1700 comprises medicaldevice communications components 1710 in a spinal instrument andreceiving system communications in a processor based remote system. Inone embodiment, the receiving remote system communications are in orcoupled to a computer or laptop computer that can be viewed by thesurgical team during a procedure. The remote system can be external tothe sterile field of the operating room but within viewing range toassess measured quantitative data in real time. The medical devicecommunications components 1710 are operatively coupled to include, butnot limited to, the antenna 1712, a matching network 1714, a telemetrytransceiver 1716, a CRC circuit 1718, a data packetizer 1722, a datainput 1724, a power source 1726, and an application specific integratedcircuit (ASIC) 1720. The medical device communications components 1710may include more or less than the number of components shown and are notlimited to those shown or the order of the components.

The receiving station communications components 1750 comprise an antenna1752, a matching network 1754, a telemetry receiver 1756, the CRCcircuit 1758, the data packetizer 1760, and optionally a USB interface1762. Notably, other interface systems can be directly coupled to thedata packetizer 1760 for processing and rendering sensor data.

Referring to FIG. 11, the electronic circuitry 1610 is operativelycoupled to one or more sensors 602 of the spinal instrument 400. In oneembodiment, the data generated by the one or more sensors 602 cancomprise a voltage, current, frequency, or count from a mems structure,piezo-resistive sensor, strain gauge, mechanical sensor, pulsed,continuous wave, or other sensor type that can be converted to theparameter being measured of the muscular-skeletal system. Referring backto FIG. 12, the data packetizer 1722 assembles the sensor data intopackets; this includes sensor information received or processed by ASIC1720. The ASIC 1720 can comprise specific modules for efficientlyperforming core signal processing functions of the medical devicecommunications components 1710. A benefit of ASIC 1720 is in reducing aform factor of the tool.

The CRC circuit 1718 applies error code detection on the packet data.The cyclic redundancy check is based on an algorithm that computes achecksum for a data stream or packet of any length. These checksums canbe used to detect interference or accidental alteration of data duringtransmission. Cyclic redundancy checks are especially good at detectingerrors caused by electrical noise and therefore enable robust protectionagainst improper processing of corrupted data in environments havinghigh levels of electromagnetic activity. The telemetry transmitter 1716then transmits the CRC encoded data packet through the matching network1714 by way of the antenna 1712. The matching networks 1714 and 1754provide an impedance match for achieving optimal communication powerefficiency.

The receiving system communications components 1750 receivetransmissions sent by spinal instrument communications components 1710.In one embodiment, telemetry transmitter 1716 is operated in conjunctionwith a dedicated telemetry receiver 1756 that is constrained to receivea data stream broadcast on the specified frequencies in the specifiedmode of emission. The telemetry receiver 1756 by way of the receivingstation antenna 1752 detects incoming transmissions at the specifiedfrequencies. The antenna 1752 can be a directional antenna that isdirected to a directional antenna of components 1710. Using at least onedirectional antenna can reduce data corruption while increasing datasecurity by further limiting the data is radiation pattern. A matchingnetwork 1754 couples to antenna 1752 to provide an impedance match thatefficiently transfers the signal from antenna 1752 to telemetry receiver1756. Telemetry receiver 1756 can reduce a carrier frequency in one ormore steps and strip off the information or data sent by components1710. Telemetry receiver 1756 couples to CRC circuit 1758. CRC circuit1758 verifies the cyclic redundancy checksum for individual packets ofdata. CRC circuit 1758 is coupled to data packetizer 1760. Datapacketizer 1760 processes the individual packets of data. In general,the data that is verified by the CRC circuit 1758 is decoded (e.g.,unpacked) and forwarded to an external data processing device, such asan external computer, for subsequent processing, display, or storage orsome combination of these.

The telemetry receiver 1756 is designed and constructed to operate onvery low power such as, but not limited to, the power available from thepowered USB port 1762, or a battery. In another embodiment, thetelemetry receiver 1756 is designed for use with a minimum ofcontrollable functions to limit opportunities for inadvertent corruptionor malicious tampering with received data. The telemetry receiver 1756can be designed and constructed to be compact, inexpensive, and easilymanufactured with standard manufacturing processes while assuringconsistently high levels of quality and reliability.

In one configuration, the communication system 1700 operates in atransmit-only operation with a broadcasting range on the order of a fewmeters to provide high security and protection against any form ofunauthorized or accidental query. The transmission range can becontrolled by the transmitted signal strength, antenna selection, or acombination of both. A high repetition rate of transmission can be usedin conjunction with the Cyclic Redundancy Check (CRC) bits embedded inthe transmitted packets of data during data capture operations therebyenabling the receiving system to discard corrupted data withoutmaterially affecting display of data or integrity of visualrepresentation of data, including but not limited to measurements ofload, force, pressure, displacement, flexion, attitude, and positionwithin operating or static physical systems.

By limiting the operating range to distances on the order of a fewmeters the telemetry transmitter 1716 can be operated at very low powerin the appropriate emission mode or modes for the chosen operatingfrequencies without compromising the repetition rate of the transmissionof data. This mode of operation also supports operation with compactantennas, such as an integrated loop antenna. The combination of lowpower and compact antennas enables the construction of, but is notlimited to, highly compact telemetry transmitters that can be used for awide range of non-medical and medical applications.

The transmitter security as well as integrity of the transmitted data isassured by operating the telemetry system within predeterminedconditions. The security of the transmitter cannot be compromisedbecause it is operated in a transmit-only mode and there is no pathwayto hack into medical device communications components. The integrity ofthe data is assured with the use of the CRC algorithm and the repetitionrate of the measurements. Limiting the broadcast range of the deviceminimizes the risk of unauthorized reception of data. Even ifunauthorized reception of the data packets should occur there arecounter measures in place that further mitigate data access. A firstmeasure is that the transmitted data packets contain only binary bitsfrom a counter along with the CRC bits. A second measure is that no datais available or required to interpret the significance of the binaryvalue broadcast at any time. A third measure that can be implemented isthat no patient or device identification data is broadcast at any time.

The telemetry transmitter 1716 can also operate in accordance with someFCC regulations. According to section 18.301 of the FCC regulations theISM bands within the USA include 6.78, 13.56, 27.12, 30.68, 915, 2450,and 5800 MHz as well as 24.125, 61.25, 122.50, and 245 GHz. Globallyother ISM bands, including 433 MHz, are defined by the InternationalTelecommunications Union in some geographic locations. The list ofprohibited frequency bands defined in 18.303 are “the following safety,search and rescue frequency bands is prohibited: 490-510 kHz, 2170-2194kHz, 8354-8374 kHz, 121.4-121.6 MHz, 156.7-156.9 MHz, and 242.8-243.2MHz.

Section 18.305 stipulates the field strength and emission levels ISMequipment must not exceed when operated outside defined ISM bands. Insummary, it may be concluded that ISM equipment may be operatedworldwide within ISM bands as well as within most other frequency bandsabove 9 KHz given that the limits on field strengths and emission levelsspecified in section 18.305 are maintained by design or by activecontrol. As an alternative, commercially available ISM transceivers,including commercially available integrated circuit ISM transceivers,may be designed to fulfill these field strengths and emission levelrequirements when used properly.

In one configuration, the telemetry transmitter 1716 can also operate inunlicensed ISM bands or in unlicensed operation of low power equipment,wherein the ISM equipment (e.g., telemetry transmitter 1716) may beoperated on ANY frequency above 9 kHz except as indicated in Section18.303 of the FCC code.

Wireless operation eliminates distortion of, or limitations on,measurements caused by the potential for physical interference by, orlimitations imposed by, wiring and cables coupling the wireless sensingmodule or device with a power source or with data collection, storage,or display equipment. Power for the sensing components and electroniccircuits is maintained within the wireless sensing module or device onan internal energy storage device. This energy storage device is chargedwith external power sources including, but not limited to, a battery orbatteries, super capacitors, capacitors, an alternating current powersupply, a radio frequency receiver, an electromagnetic induction coil, aphotoelectric cell or cells, a thermocouple or thermocouples, or anultrasound transducer or transducers. The wireless sensing module may beoperated with a single charge until the internal energy source isdrained or the energy source may be recharged periodically to enablecontinuous operation. The embedded power supply minimizes additionalsources of energy radiation required to power the wireless sensingmodule or device during measurement operations. Telemetry functions arealso integrated within the wireless sensing module or device. Onceinitiated the telemetry transmitter continuously broadcasts measurementdata in real time. Telemetry data may be received and decoded withcommercial receivers or with a simple, low cost custom receiver.

FIG. 13 illustrates a communication network 1800 for measurement andreporting in accordance with an example embodiment. Briefly, thecommunication network 1800 expands communication for spine measurementsystem 100 of FIG. 1, spinal instrument 400 of FIG. 2, spinal instrument410 of FIG. 3, and insert instrument 420 to provide broad dataconnectivity to other devices or services. As illustrated, spinalalignment system 100, spinal instrument 400, and insert instrument 420can be communicatively coupled to the communications network 1800 andany associated systems or services. It should be noted thatcommunication network 1800 can comprise more or less than the number ofcommunication networks and systems shown.

As one example, measurement system 100, spinal instrument 400, spinalinstrument 410, and insert instrument 420 can share its parameters ofinterest (e.g., distributions of load, force, pressure, displacement,movement, rotation, torque and acceleration) with remote services orproviders, for instance, to analyze or report on surgical status oroutcome. In the case that a sensor system is permanently implanted, thedata from the sensor can be shared for example with a service providerto monitor progress or with plan administrators for surgical planningpurposes or efficacy studies. The communication network 1800 can furtherbe tied to an Electronic Medical Records (EMR) system to implementhealth information technology practices. In other embodiments, thecommunication network 1800 can be communicatively coupled to HISHospital Information System, HIT Hospital Information Technology and HIMHospital Information Management, EHR Electronic Health Record, CPOEComputerized Physician Order Entry, and CDSS Computerized DecisionSupport Systems. This provides the ability of different informationtechnology systems and software applications to communicate, to exchangedata accurately, effectively, and consistently, and to use the exchangeddata.

The communications network 1800 can provide wired or wirelessconnectivity over a Local Area Network (LAN) 1801, a Wireless Local AreaNetwork (WLAN) 1805, a Cellular Network 1814, and/or other radiofrequency (RF) system. The LAN 1801 and WLAN 1805 can be communicativelycoupled to the Internet 1820, for example, through a central office. Thecentral office can house common network switching equipment fordistributing telecommunication services. Telecommunication services caninclude traditional POTS (Plain Old Telephone Service) and broadbandservices such as cable, HDTV, DSL, VoIP (Voice over Internet Protocol),IPTV (Internet Protocol Television), Internet services, and so on.

The communication network 1800 can utilize common computing andcommunications technologies to support circuit-switched and/orpacket-switched communications. Each of the standards for Internet 1820and other packet switched network transmission (e.g., TCP/IP, UDP/IP,HTML, HTTP, RTP, MMS, SMS) represent examples of the state of the art.Such standards are periodically superseded by faster or more efficientequivalents having essentially the same functions. Accordingly,replacement standards and protocols having the same functions areconsidered equivalent.

The cellular network 1814 can support voice and data services over anumber of access technologies such as GSM-GPRS, EDGE, CDMA, UMTS, WiMAX,2G, 3G, WAP, software defined radio (SDR), and other known technologies.The cellular network 1814 can be coupled to base receiver 1810 under afrequency-reuse plan for communicating with mobile devices 1802.

The base receiver 1810, in turn, can connect the mobile device 1802 tothe Internet 1820 over a packet switched link. Internet 1820 can supportapplication services and service layers for distributing data fromspinal alignment system 100, spinal instrument 400, and insertinstrument 420 to the mobile device 502. The mobile device 1802 can alsoconnect to other communication devices through the Internet 1820 using awireless communication channel.

The mobile device 1802 can also connect to the Internet 1820 over theWLAN 1805. Wireless Local Access Networks (WLANs) provide wirelessaccess within a local geographical area. WLANs are typically composed ofa cluster of Access Points (APs) 1804 also known as base stations.Spinal alignment system 100, spinal instrument 400, and insertinstrument 420 can communicate with other WLAN stations such as laptop1803 within the base station area. In typical WLAN implementations, thephysical layer uses a variety of technologies such as 802.11b or 802.11gWLAN technologies. The physical layer may use infrared, frequencyhopping spread spectrum in the 2.4 GHz Band, direct sequence spreadspectrum in the 2.4 GHz Band, or other access technologies, for example,in the 5.8 GHz ISM band or higher ISM bands (e.g., 24 GHz, etc.).

By way of the communication network 1800, spinal alignment system 100,spinal instrument 400, and insert instrument 420 can establishconnections with a remote server 1830 on the network and with othermobile devices for exchanging data. The remote server 1830 can haveaccess to a database 1840 that is stored locally or remotely and whichcan contain application specific data. The remote server 1830 can alsohost application services directly, or over the internet 1820.

FIG. 14 depicts an exemplary diagrammatic representation of a machine inthe form of a computer system 1900 within which a set of instructions,when executed, may cause the machine to perform any one or more of themethodologies discussed above. In some embodiments, the machine operatesas a standalone device. In some embodiments, the machine may beconnected (e.g., using a network) to other machines. In a networkeddeployment, the machine may operate in the capacity of a server or aclient user machine in server-client user network environment, or as apeer machine in a peer-to-peer (or distributed) network environment.

The machine may comprise a server computer, a client user computer, apersonal computer (PC), a tablet PC, a laptop computer, a desktopcomputer, a control system, a network router, switch or bridge, or anymachine capable of executing a set of instructions (sequential orotherwise) that specify actions to be taken by that machine. It will beunderstood that a device of the present disclosure includes broadly anyelectronic device that provides voice, video or data communication.Further, while a single machine is illustrated, the term “machine” shallalso be taken to include any collection of machines that individually orjointly execute a set (or multiple sets) of instructions to perform anyone or more of the methodologies discussed herein.

The computer system 1900 may include a processor 1902 (e.g., a centralprocessing unit (CPU), a graphics processing unit (GPU, or both), a mainmemory 1904 and a static memory 1906, which communicate with each othervia a bus 1908. The computer system 1900 may further include a videodisplay unit 1910 (e.g., a liquid crystal display (LCD), a flat panel, asolid-state display, or a cathode ray tube (CRT)). The computer system1900 may include an input device 1912 (e.g., a keyboard), a cursorcontrol device 1914 (e.g., a mouse), a disk drive unit 1916, a signalgeneration device 1918 (e.g., a speaker or remote control) and a networkinterface device 1920.

The disk drive unit 1916 may include a machine-readable medium 1922 onwhich is stored one or more sets of instructions (e.g., software 1924)embodying any one or more of the methodologies or functions describedherein, including those methods illustrated above. The instructions 1924may also reside, completely or at least partially, within the mainmemory 1904, the static memory 1906, and/or within the processor 1902during execution thereof by the computer system 1900. The main memory1904 and the processor 1902 also may constitute machine-readable media.

Dedicated hardware implementations including, but not limited to,application specific integrated circuits, programmable logic arrays andother hardware devices can likewise be constructed to implement themethods described herein. Applications that may include the apparatusand systems of various embodiments broadly include a variety ofelectronic and computer systems. Some embodiments implement functions intwo or more specific interconnected hardware modules or devices withrelated control and data signals communicated between and through themodules, or as portions of an application-specific integrated circuit.Thus, the example system is applicable to software, firmware, andhardware implementations.

In accordance with various embodiments of the present disclosure, themethods described herein are intended for operation as software programsrunning on a processor, digital signal processor, or logic circuitry.Furthermore, software implementations can include, but not limited to,distributed processing or component/object distributed processing,parallel processing, or virtual machine processing can also beconstructed to implement the methods described herein.

The present disclosure contemplates a machine readable medium containinginstructions 1924, or that which receives and executes instructions 1924from a propagated signal so that a device connected to a networkenvironment 1926 can send or receive voice, video or data, and tocommunicate over the network 1926 using the instructions 1924. Theinstructions 1924 may further be transmitted or received over a network1926 via the network interface device 1920.

While the machine-readable medium 1922 is shown in an example embodimentto be a single medium, the term “machine-readable medium” should betaken to include a single medium or multiple media (e.g., a centralizedor distributed database, and/or associated caches and servers) thatstore the one or more sets of instructions. The term “machine-readablemedium” shall also be taken to include any medium that is capable ofstoring, encoding or carrying a set of instructions for execution by themachine and that cause the machine to perform any one or more of themethodologies of the present disclosure.

The term “machine-readable medium” shall accordingly be taken toinclude, but not be limited to: solid-state memories such as a memorycard or other package that houses one or more read-only (non-volatile)memories, random access memories, or other re-writable (volatile)memories; magneto-optical or optical medium such as a disk or tape; andcarrier wave signals such as a signal embodying computer instructions ina transmission medium; and/or a digital file attachment to e-mail orother self-contained information archive or set of archives isconsidered a distribution medium equivalent to a tangible storagemedium. Accordingly, the disclosure is considered to include any one ormore of a machine-readable medium or a distribution medium, as listedherein and including art-recognized equivalents and successor media, inwhich the software implementations herein are stored.

Although the present specification describes components and functionsimplemented in the embodiments with reference to particular standardsand protocols, the disclosure is not limited to such standards andprotocols. Each of the standards for Internet and other packet switchednetwork transmission (e.g., TCP/IP, UDP/IP, HTML, HTTP) representexamples of the state of the art. Such standards are periodicallysuperseded by faster or more efficient equivalents having essentiallythe same functions. Accordingly, replacement standards and protocolshaving the same functions are considered equivalents.

The illustrations of embodiments described herein are intended toprovide a general understanding of the structure of various embodiments,and they are not intended to serve as a complete description of all theelements and features of apparatus and systems that might make use ofthe structures described herein. Many other embodiments will be apparentto those of skill in the art upon reviewing the above description. Otherembodiments may be utilized and derived therefrom, such that structuraland logical substitutions and changes may be made without departing fromthe scope of this disclosure. Figures are also merely representationaland may not be drawn to scale. Certain proportions thereof may beexaggerated, while others may be minimized. Accordingly, thespecification and drawings are to be regarded in an illustrative ratherthan a restrictive sense.

Such embodiments of the inventive subject matter may be referred toherein, individually and/or collectively, by the term “invention” merelyfor convenience and without intending to voluntarily limit the scope ofthis application to any single invention or inventive concept if morethan one is in fact disclosed. Thus, although specific embodiments havebeen illustrated and described herein, it should be appreciated that anyarrangement calculated to achieve the same purpose may be substitutedfor the specific embodiments shown. This disclosure is intended to coverany and all adaptations or variations of various embodiments.Combinations of the above embodiments, and other embodiments notspecifically described herein, will be apparent to those of skill in theart upon reviewing the above description.

FIG. 15 illustrates components of a spinal instrument 2000 in accordancewith an example embodiment. Spinal instrument 2000 is a more detailedillustration of a non-limiting example of spinal instrument 102 of FIG.1, spinal instrument 400 of FIG. 2, and spinal instrument 410 of FIG. 3.Spinal instrument 2000 is a measurement device having a sensored head2002 that incorporates at least one sensor for measuring a parameter ofthe spine. Spinal instrument 2000 comprises sensored head 2002, sensors2008, shaft 2010, electronic assembly 2024, interconnect 2028, andhandle 2030. In one embodiment, handle 2030 is formed by couplingstructures 2020 and 2022 together. A proximal end 2018 of shaft 2010couples to a distal end of handle 2030. A proximal end of sensored head2002 couples to a distal end 2014 of shaft 2010. Handle 2030 can be heldby a surgeon to guide the instrument into the spine region of a patientto take one or more quantitative measurements. Sensored head 2002 can beinserted into the spine region such that the sensors 2008 can measurethe parameters of interest. Electronic assembly 2024 operatively couplesto sensors 2008 to receive, process, and provide quantitativemeasurement data. In general, spinal instrument 2000 can providequantitative measurement data of a probed region by sensors 2008 mountedon or in sensored head 2002. The quantitative data can also support theinstallation of a component into the muscular-skeletal region.Quantitative data or information related to the procedure can bedisplayed on an interface 2038 that may be included in spinal instrument2000. Alternatively, spinal instrument 2000 can provide quantitativedata in support of a procedure through a remote system as disclosedherein. The remote system can be wired or wirelessly coupled to spinalinstrument 2000. The quantitative data can be provided in real-time withvisualization of the procedure.

In the example, sensored head 2002 comprises a support structure 2004and a support structure 2006. Support structures 2004 and 2006 can movein relation to one another. For example, a compressive force can beapplied to external surfaces of support structures 2004 and 2006.Structures 2004 and 2006 can move under the compressive force resultingin a change of height of sensored head 2002. In general, the externalsurfaces of support structures 2004 and 2006 would move closer togetheras the applied force or pressure increases. In one embodiment, themovement or change in distance between the external surfaces of supportstructures 2004 and 2006 is small in relation to the height of sensoredhead 2002 when no compressive force is applied.

Sensors 2008 are shown disassembled from sensored head 2002. Sensors2008 are placed within sensored head 2002 when assembled. Sensors 2008couple between interior surfaces of support structures 2004 and 2006. Acompressive force, pressure, or load applied to exterior surfaces ofsupport structures 2004 and 2006 couples to sensors 2008. A measurableparameter of a sensor may directly or indirectly correspond to theforce, pressure, or load applied thereto. In one embodiment sensors 2008are film sensors having a low profile. An example of a film sensor is apiezo-resistive sensor or a polymer sensor. Piezo-resistive film sensorschange resistance with an applied force, pressure, or load. Other sensortypes can be used as disclosed herein. In general, each sensor islocated at a predetermined position within sensored head 2002. Thepredetermined position can couple to a predetermined location on theexternal surfaces of support structures 2004 and 2006. Locating eachsensor at a known predetermined position supports the determination ofthe location of applied load to exterior surfaces of support structures2004 and 2006. As shown, four sensors are placed within sensored head2002. Typically more than one sensor is used to determine location ofapplied load. The load measurements of sensors 2008 are assessed inrelation with the corresponding location of each sensor. For example,the sensor nearest to the applied load will measure the highest loadmagnitude. Conversely, the sensor farthest from the applied load willmeasure the lowest load magnitude. Each sensor measurement can be usedin the determination of the location where the load is applied to theexterior surfaces of support structures 2004 and 2006 and the magnitudeof the applied load at the identified location.

The resistance of a piezo-resistive film sensor corresponds to thethickness of the film. An applied pressure to piezo-resistive filmsensor reduces the thickness thereby lowering the resistance. Thesurface area of each piezo-resistive sensor is selected to fit withinsensored head 2002 and relate to a predetermined location on theexternal surfaces of support structures 2004 and 2006 for locationidentification. The surface area of sensors 2008 corresponds to therange of resistance being measured over the measurable load range ofspinal instrument 2000. Typically, the magnitude and change in magnitudeof the measurable parameter of sensors 2008 over the specified loadrange is known or measured.

A voltage or current is typically provided by electronic assembly 2024to piezo-resistive film sensors. For example, providing a known currentto the piezo-resistive film sensor generates a voltage that correspondsto the resistance. The voltage can be measured by electronic assembly2024 and translated to a load measurement. Similarly, a known voltagecan be applied to the piezo-resistive film sensor. The current conductedby the piezo-resistive film sensor corresponds to the resistance of thedevice. The current can be measured by electronic assembly 2024 andtranslated to the load measurement. Accuracy of the measurement can beimproved by calibration of each sensor and providing the calibrationdata to electronic assembly 2024 for providing correction to themeasured data. The calibration can compare sensor measurements to knownloads applied to sensored head 2002. Calibration can occur overdifferent operating conditions such as temperature. In one embodiment,sensors 2008 may be calibrated as part of a final test of spinalinstrument 2000.

As mentioned previously, sensors 2008 comprise four sensors that supportthe measurement of the position of loading applied to at least one ofthe external surfaces of support structures 2004 and 2006. In oneembodiment, support structures 2004 and 2006 have convex shaped externalsurfaces that aid in the insertion of sensored head 2002 into the spinalregion such as between vertebrae. The height of sensored head 2002 is adistance between the external surfaces of the support structures 2004and 2006. Sensored head can be used to distract and generate a gapbetween vertebrae. For example, the surgeon selects a sensored head of apredetermined height to produce a gap approximately equal to thesensored head height.

Shaft 2010 provides a separation distance between handle 2030 andsensored head 2002. The shaft 2010 allows the surgeon to view and directsensored head 2002 of spinal instrument 2000 into an exposed area of thespine. A distal end 2014 of the shaft 2010 fits into and fastens to aproximal end 2016 of sensored head 2002. In one embodiment, shaft 2010is cylindrical in shape and includes at least one lengthwise passage2012. Proximal end 2016 of sensored head 2002 can include an opening forreceiving distal end 2014 of shaft 2010. The shaft 2010 can be securedin the opening of sensored head 2002 by mechanical, adhesive, welding,bonding or other attaching method. In one embodiment, the attachingprocess permanently affixes sensored head 2002 to shaft 2010. Thelengthwise passage 2012 of shaft 2010 may be used to couple a componentfrom handle 2030 to sensored head 2002. For example, an interconnect2028 can couple through the lengthwise passage 2012. The interconnect2028 extends out of the lengthwise passage 2012 on both distal end 2014and proximal end 2018 of shaft 2010. Interconnect 2028 couples sensors2008 to electronic assembly 2024. Similarly, a second lengthwise passagein shaft 2010 can support a threaded rod that couples to a scissor jackwithin sensor head 2002 for raising and lowering support structures 2004and 2006 as disclosed herein. Although a cylindrical shape is disclosed,shaft 2010 can be formed having other shapes. In the example, shaft 2010is rigid and does not bend or flex when used to insert sensored head2002 into the spine region. In one embodiment, handle 2030, shaft 2010,support structure 2004, and 2006 are formed of a polymer material suchas polycarbonate. Alternatively, spinal instrument can comprise metalcomponents or a combination of polymer and metal to form the structure.The metal components can comprise stainless steel.

Handle 2030 comprises a structure 2020 and a structure 2022. Thestructures 2020 and 2022 can be formed to include one or more cavities,slots, or openings. A cavity 2026 is shaped to receive electronicassembly 2024 that is housed in handle 2030. The cavity 2026 can includeone or more features to support and retain electronic assembly 2024. Aslot 2032 can be used to guide and retain interconnect 2028 toelectronic assembly 2024 for coupling. Structures 2020 and 2022 coupletogether to form handle 2030. An opening 2034 on the distal end ofhandle 2030 receives proximal end 2018 of shaft 2010. In one embodiment,structures 2020 and 2022 can be formed of a polymer or metal. In theexample, sensored head 2002, shaft 2010, and structures 2020 and 2022can be formed by a molding process using a polymer material such aspolycarbonate. The structures 2020 and 2022 can be fastened together bymechanical, adhesive, welding, bonding or other attaching method.Similarly, proximal end 2018 of shaft 2010 can be coupled to opening2034 on the distal end of handle 2030 by mechanical, adhesive, welding,bonding, or other attaching method. In general, the active circuitrywithin spinal instrument 2000 is isolated from the external environmentand a rigid device is formed when sensored head 2002, shaft 2010, andhandle 2030 are coupled together. In one embodiment, the sealing processis permanent and spinal instrument 2000 cannot be disassembled toreplace components such as the power source (e.g. batteries) that can beincluded in electronic assembly 2024. The handle 2030 can be formedhaving a shape that is ergonomic for positioning spinal instrument 2000.The handle 2030 can include weights placed in interior cavities thatimprove the feel and balance of the device for the surgical procedure.Reinforcement structures can be added to stiffen spinal instrument 2000thereby reducing device flex. The proximal end of handle 2030 includes aflange 2036 for being tapped by a hammer to aid in the insertion ofsensored head 2002 into the spinal region. The flange is sized to accepta standard slap-hammer to aid in the removal of the sensor head from thespinal region. Flange 2036 and the proximal end of handle 2030 arereinforced to withstand hammer taps by the surgeon.

Electronic assembly 2024 controls a measurement process of spinalinstrument 2000. In the example, the components of the system aremounted to a printed circuit board. The printed circuit board can havemultiple layers of interconnect. Components can be mounted on both sidesof the printed circuit board. In one embodiment, the printed circuitboard includes a connector 2040 for receiving and retaining interconnect2028. In the example, interconnect 2028 can be a flexible planarinterconnect having copper traces thereon comprising five interconnectsfor coupling to sensors 2008. A power source such as a battery can bemounted to the printed circuit board for powering electronic assembly2024. Communication circuitry of electronic assembly 2024 can wirelesslytransmit measurement data to a remote system for viewing in real-time.Spinal instrument 2000 can also receive information or data through awired or wireless connection. Spinal instrument 2000 can include display2038 with a GUI to locally provide data to the surgeon. Spinalinstrument 2000 can also be operatively coupled via a remote sensorsystem to allow control or feedback through vocal, visual, haptic,gestures, or other communicative means to simplify a workflow or reducestaff required for the procedure.

FIG. 16 illustrates a spine measurement system 2100 for providingintervertebral load and position of load data in accordance with anexample embodiment. Spine measurement system 2100 is a more detailedillustration of a non-limiting example of spine measurement system 100of FIG. 1. System 2100 can also include an insert instrument andexternal alignment devices. The system 2100 comprises spinal instruments2102A-F (2102A, 2102B, 2102C, 2102D, 2102E, and 2102F) that includeactive circuitry for measuring a parameter of the muscular-skeletalsystem. Spinal instruments 2102A-F are a non-limiting example of spinalinstrument 400 of FIG. 2, spinal instrument 410 of FIG. 3, and spinalinstrument 2000. In the example, spinal instruments 2102A-F each includeone or more sensors to measure load and position of load.

The system 2100 comprises a set of spinal instruments 2102A-F where eachtool has a different distraction height. Spinal instruments can also beprovided having sensored heads of different lengths. As shown, the setof spinal instruments 2102A-F have a sensored head length 2120. Anexample of sensored heads having different head lengths is disclosedbelow and can be adapted to system 2100. Each spinal instrument 2102A,2102B, 2102C, 2102D, 2102E, and 2102F respectively has sensored heads2104A, 2104B, 2104C, 2104D, 2104E, and 2104F. The surgeon selects thespinal instrument for an appropriate sensored head height that distractsa spinal region appropriate for a patient physiology. As shown, the sixsensored heads 2104A, 2104B, 2104C, 2104D, 2104E, and 2104F respectivelyhave heights A, B, C, D, E, and F. The six different heights A-F ofsensored heads 2104A-F are an example of what might be provided in atypical system. An example of a distraction height range for a set ofsensored heads can be from 6 millimeters to 14 millimeters. An examplerange of the length of a sensored head can be from 22 millimeters to 36millimeters. In general, the different height and lengths of sensoredheads 2104A-F of system 2100 are chosen to cover a statisticallysignificant portion a patient population a surgeon is likely to see. Theactual number of sensored heads having different height and lengths canvary depending on the application. In one embodiment, sensored headheight and lengths that are out of the norm can be inventoried in theoperating room but may not be part of the set provided initially duringthe procedure. The inventoried sensored heads can be made available tothe surgeon in the event that the set does not provide a suitablesensored head height and length for the patient.

In general, spine measurement system 2100 measures a parameter of thespinal region. In the example, load and position of load are measured.Spinal instruments 2102A-F can also measure the location and position in3D space with one or more internal accelerometers within each tool. Inone embodiment, an accelerometer identifies the trajectory, location andposition of the sensored head in real-time. The accelerometer can belocated in the handle of spinal instruments 2102A-F with the electronicassembly. The one or more parameter measurements output by system 2100provide quantitative data to support the procedure. For example, thesurgeon exposes the spinal region and views the area of interest. Thespinal instruments 2102A-F is made available such that the surgeon canselect and use at least one of the tools. Remote system 105 is typicallyplaced outside the sterile field of the operating room. In oneembodiment, each spinal instrument 2102A-F may be stored in individualsterilized packaging that is not opened until the surgeon views thespinal region being repaired. The selection of a spinal instrument ispatient specific due to variations in spine gap and patient physiology.In the example, the surgeon first determines the appropriate gap heightand then opens a sterile package having the spinal instrument with thesensored head of the selected height. In one embodiment, the selectedspinal instrument can be placed by a device that can initiate a power upsequence. The enabling process couples an internal power source of thetool to the electronic circuitry and sensors therein. Once powered up,the selected spinal instrument can be coupled to remote system 105.Remote system 105 receives and displays data from the selected spinalinstrument. Remote system 105 includes a GUI 107 for controlling userinteraction and providing data on a display. The GUI 107 can providedifferent screens or windows at different steps of the procedure as aworkflow that provides quantitative data to the surgeon in one or moreformats such that the data supports the surgical outcome.

The surgeon holds the selected spinal instrument by the handle anddirects the sensored head between the vertebrae. The enabled spinalinstrument sends load, position of load, instrument position, andlocation data to the remote system 105 where it is displayed inreal-time. As mentioned herein, the exterior surfaces of the sensoredhead are convex in shape such that the tip is narrowed allowingpenetration between a separated space between vertebrae prior todistraction. The amount of force required to distract vertebrae canvary. A controlled force applied to the selected spinal instrument maybe required to increase the opening between vertebrae. For example, ahammer can be used to tap the flange at the end of the handle of theselected spinal instrument to insert the sensored head between thevertebrae.

In the example, the final position of the sensored head corresponds tothe location where a component such as a spinal cage can be placed in asubsequent step. The spinal cage would have a height and lengthsubstantially equal to the height and length of the sensored head of theselected spinal instrument. System 2100 measures and displaysquantitative data from the selected spinal instrument such astrajectory, position, location, loading, and position of loading of thesensored head. The data supports the placement of the component in thelocation. More specifically, the loading and position of load on thecomponent placed between the vertebrae can be substantial equal to thequantitative measurements from the selected spinal instrument when thecomponent is placed and located in the final position of the sensoredhead when distracting the vertebrae.

The surgeon may find that the selected spinal instrument has a sensoredhead height that is larger or smaller than needed. The surgeon uses asmany spinal instruments as required to distract the vertebrae to anappropriate height. This similarly applies to the selection of spinalinstruments of different lengths. In one embodiment, the power sourcewithin each spinal instruments 2102A-F can power the tool for only asingle procedure. Moreover, spinal instruments 2102A-F may not becapable of being sterilized for reuse without compromising the integrityof the device. The spinal instruments that have been removed fromsterilized packaging can be disposed of after the surgical procedure isperformed. The spinal instruments that remain in sterile packaging canbe used in another procedure. The spinal instruments that are disposedof after being used can be replaced to complete the set.

An alternate approach can use a passive set of spinal instruments to dothe initial distraction. The passive spinal instruments have nomeasurement capability. The surgeon identifies an appropriatedistraction height between vertebrae with the passive spinalinstruments. The set of passive spinal instruments have heads with equalheights as spinal instruments 2102A-F. A spinal instrument is thenselected from spinal instruments 2102A-F having a height equal to theidentified distraction height made by the passive spinal instrument. Theselected spinal instrument is then inserted between the vertebrae.Quantitative data measurements are then taken by the selected spinalinstrument in preparation for implanting a component between thevertebrae. The passive spinal instruments can also be low costdisposable or tools that can be sterilized after use. The alternateapproach provides the benefit of minimizing the number of spinalinstruments 2102A-F used in the procedure.

A method of providing spinal instruments to an operating room isdisclosed below. The steps of the method can be performed in any order.The example comprises a system that includes more than one spinalinstruments having active circuitry for measurement of a spinal region.The non-limiting example is used to demonstrate a method that isapplicable to other muscular-skeletal regions such as the knee, hip,ankle, spine, shoulder, hand, arm, and foot. In a first step, more thanone spinal instrument is provided within the operating room. The spinalinstruments are in individually sterilized packaging. In one embodiment,the spinal instruments each have a different distraction height andlength. The surgeon exposes the spinal region and assesses the patientphysiology. In a second step, one of the spinal instruments is selected.In the example, the spinal instrument is selected having an appropriatedistraction height for the patient. The spinal instrument is used tomeasure a parameter of the spinal region such as load and position ofload. In a third step, the selected spinal instrument is removed fromthe sterilized packaging. In a fourth step, the selected spinalinstrument is enabled. In the example, the enabling process couples aninternal power source to the circuitry in the selected spinal instrumentthereby powering up the device for generating quantitative measurementdata.

Powering up the selected spinal instrument enables communicationcircuitry within the device. In a fifth step, the selected spinalinstrument couples to a remote system. In the example, the remote systemis in the operating room within viewing range of the surgeon. The remotesystem includes a display for presenting the quantitative measured datafrom the selected spinal instrument. The remote system can indicate thatthe selected spinal instrument is enabled by audio, visual, or hapticfeedback.

The distraction height can be determined using passive spinaldistraction instruments prior to selecting the active spinal instrument.The surgeon selects a passive spinal instrument after the spine regionis assessed or exposed. In a sixth step, the spinal region is distractedusing the selected passive spinal instrument. The passive spinalinstruments have no active circuitry for measurement. In the example, aset of passive spinal instruments has identical heights and lengths asthe set of active spinal instruments. In a seventh step, the passivespinal instrument is removed from the spinal region after distractionwith the selected passive spinal instrument. In an eighth step, theselected spinal instrument is inserted in the spinal region previouslydistracted by the selected passive spinal instrument. In the example,the selected spinal instrument has the same height and length as theselected passive spinal instrument. In a ninth step, the selected spinalinstrument takes parameter measurements. The data can be wirelesslytransmitted to a remote system for display or visualization of theprocedure.

One or more of the active spinal instruments can be used during theprocedure. In a tenth step, the active spinal instruments that were usedto take measurements of the spinal region are disposed of after theprocedure. In one embodiment, the passive spinal instruments can gothrough a sterilization process and are not disposed. Alternatively, theused passive spinal instruments can be disposed similar to the activespinal instruments. In an eleventh step, the spinal instruments thatwere used and disposed of are replaced. The replacements re-complete theset for a subsequent procedure. The remaining active spinal instrumentsthat were not used are sterile as their sterilized packaging was notopened during the procedure and thus can be reused.

FIG. 17 illustrates a spine measurement system 2200 for providingintervertebral load and position of load data in accordance with anexample embodiment. Spine measurement system 2200 is a more detailedillustration of a non-limiting example of spine measurement system 100of FIG. 1. The system 2200 comprises a remote system 105 and a modularspinal instrument. System 2200 can also include an insert instrument andexternal alignment devices. The modular spinal instrument comprises ahandle 2206, a shaft 2208, a plurality of removable sensored heads2204A-F, and a module 2210. In general, the spinal instrument is amodular active device having components that can be coupled to handle2206 and shaft 2208. Three sets of removable sensored heads 2204A-F(2204A, 2204B, 2204C, 2204D, 2204E, and 2204F), 2216A-F (2216A, 2216B,2216C, 2216D, 2216E, and 2216F), and 2218A-F (2218A, 2218B, 2218C,2218D, 2218E, and 2218F) are shown in system 2200. There can be more orless than three sets of sensored heads provided in system 2200. Sensoredheads 2204A-F, 2216A-F, and 2218A-F can be coupled to or removed fromthe distal end of shaft 2208. Similarly, module 2210 can be coupled toor removed from a cavity 2214 of handle 2206. An external surface ofmodule 2210 can be shaped as part of an exterior surface of handle 2206when attached. Module 2210 includes an electrical assembly 2212comprising electronic circuitry for receiving, processing, and sendingquantitative data from sensors in a sensored head. Module 2210 can alsoinclude a power source for powering spinal instrument 2202 during aprocedure. Electrical interfaces and interconnect couple module 2210 toone of sensored heads 2204A-F when respectively assembled to handle 2206and shaft 2208.

In general, sensored heads of different heights and different lengthsare provided as part of the system for supporting spine measurementsover a large statistical population of spine anatomy. The concept can beapplied to the configuration disclosed in FIG. 16 where additional setsof spinal instruments can be provided having different sensored headlengths. The modular spinal instrument is a measurement device and adistractor. Removable sensored heads 2204A, 2204B, 2204C, 2204D, 2204E,and 2204F respectively have a sensored head height of A, B, C, D, E, andF. Similarly, removable sensored heads 2216A, 2216B, 2216C, 2216D,2216E, and 2216F and 2218A, 2218B, 2218C, 2218D, 2218E, and 2218Frespectively have head height A, B, C, D, E, and F. The six differentheights A-F of sensored heads 2204A-F are an example of what might beprovided in a typical system. Each set can set can have more or lessthan the number of heights show. As mentioned previously, an examplerange for sensored head heights can be 6 millimeters to 14 millimeters.Sensored heads 2204A-F, 2216 A-F, and 2218A-F respectively have asensored head length of 2220, 2222, and 2224. The surgeon selects theappropriate sensored head length based on the patient spine anatomy. Anexample range for sensored head lengths can be from 22 millimeters to 36millimeters.

The actual number of sensored heads having different heights can varydepending on the application. In one embodiment, sensored head heightand length that are out of the norm can be inventoried in the operatingroom but may not be part of the set provided within the surgical fieldof the operating room. They can be made available to the surgeon in theevent that the set does not provide a suitable sensored head height andlength for the patient. The sensored head of spinal instrument 2202 isinserted in the spinal region thereby generating a gap or spacingapproximately equal to the height of the sensored head. Spinalinstrument 2202A-F is a non-limiting example of spinal instrument 400 ofFIG. 2 and spinal instrument 410 of FIG. 3. In the example, spinalinstruments 2202A-F includes one or more sensors to measure load andposition of load.

In general, system 2200 can be used in an operating room to providequantitative measurements on the spinal region. A surgeon exposes andreviews the spinal region prior to distraction. The surgeon may selectone of the sets of sensored heads 2204A-F, 2216A-F, and 2218A-Frespectively having the sensored head lengths 2220, 2222, and 2224. Forexample, the surgeon chooses the set of sensored heads 2204A-F havingthe shortest head length 2220. The surgeon can then select one ofsensored heads 2204A-F having a height that distracts the spinal regionappropriate for a patient physiology. In one embodiment, sensored heads2204A-F are in individual sterilized packaging. The selected sensoredhead is removed from the individual sterilized packaging. The surgeoncouples the selected sensored head to the distal end of shaft 2208.Similarly, module 2210 is removed from sterilized packaging andinstalled in handle 2206. System 2200 is then enabled for providingquantitative data from spinal instrument 2202. The enabling process cancouple an internal power source of the tool to the electronic circuitryand sensors therein. Once powered up, the selected spinal instrument canbe coupled to remote system 105. Remote system 105 will provideindication that spinal instrument 2202 is enabled and operating. Remotesystem 105 receives and displays data from the selected spinalinstrument. Remote system 105 includes a GUI 107 for initiating aworkflow, controlling user interaction, and providing data on a display.The GUI 107 can provide different screens or windows at different stepsof the procedure as a workflow that provides quantitative data to thesurgeon in or more formats such that the data supports the surgicaloutcome.

The surgeon during the procedure may find that the selected sensoredhead has a height that is larger or smaller than needed. Spinalinstrument 2202 can be removed from the spinal region to replace thesensored head. The sensored head can be replaced as many times asnecessary until an appropriate distraction height is achieved and thequantitative measurements of spinal instrument 2202 provide assessmentof the spinal region. In one embodiment, the power source within module2210 can power the tool for a single surgical application. Module 2210can be sealed to prevent replacement of the power source. Furthermore,after a completed procedure, module 2210 and used sensored heads 2204A-Fare disposed of in a manner to prevent reuse. A complete set of sensoredheads 2204A-F can be made for a subsequent procedure by replacing theused sensored heads and combining with the unused remaining sensoredheads 2204A-F. Spinal instrument 2202 provides the benefit of loweringcost by replacing only a portion of the system.

A method of measuring a spinal region is disclosed below. The steps ofthe method can be performed in any order. The example comprises a spinalinstrument having active circuitry for measuring a parameter, position,and trajectory. The spinal instrument can be used to distract the spinalregion. The spinal instrument is modular allowing rapid changes during aprocedure to change a distraction height. The non-limiting example isused to demonstrate a method that is applicable to othermuscular-skeletal regions such as the knee, hip, ankle, spine, shoulder,hand, arm, and foot.

In a first step, one of a plurality of removable sensored heads isselected. The plurality of sensored heads comprises a set where eachsensored head has a different height. One or more sets of sensored headscan be provided where the sensored heads of a set have a different headlength than the other sets. In one embodiment, each sensored head is inan individual sterilized package. The selected sensored head is removedfrom the sterilized packaging. In a second step, a selected sensoredhead is coupled to a distal end of a shaft of the instrument. In oneembodiment, the sensored head and the shaft respectively have a femaleand male coupling. The male coupling is inserted into the femalecoupling and locked into place. The locking step can be a rotation ofthe sensored head to a position that includes one or more retainingfeatures. In a third step, a module is coupled to the spinal instrument.The module includes an electronic assembly for receiving data fromsensors in the sensored head. In one embodiment, the module is placed ina cavity of the handle. The module includes a retaining feature thatlocks it into place in the handle but allows removal of the module. Theelectronic assembly operatively couples to the sensored head viaelectrical interfaces and interconnect in the instrument. The instrumentcan be enabled for taking measurements during the distraction process.

In a fourth step, the sensored head on the instrument is removed. In oneembodiment, the active circuitry in the instrument is disabled prior tothe sensored head removal process. In the example, the sensored head isrotated back from the locked position such that the shaft can bewithdrawn. In a fifth step, a sensored head is selected from theremaining sensored heads. Typically, the previous sensored head isreplaced to select a different distraction height based on the patientphysiology. As before, the newly selected sensored head is removed fromthe individualized sterilized packaging. In a sixth step, the newlyselected sensored head is coupled to the distal end of the shaft of theinstrument as disclosed above. In a seventh step, the instrument isenabled for generating quantitative measurement data on themuscular-skeletal system. The process of enabling couples a power sourcewithin the module to the electronic assembly to power the instrument. Inone embodiment, the power source is disconnected from the electronicassembly while in the sterilized packaging to prevent discharge andmaximize life. In an eighth step, the used sensored heads and the moduleare disposed of after a procedure. The sensored head and the module areremoved from the instrument and disposed of appropriately. In oneembodiment, the main body of the instrument comprising the handle andshaft can be sterilized for a subsequent procedure.

FIG. 18 illustrates an exploded view of module 2210 and handle 2206 inaccordance with an example embodiment. Module 2210 and handle 2206 arepart of spinal instrument 2202 of FIG. 17. Reference can be made tocomponents of FIG. 17 and FIG. 18. A removable module 2210 is anon-limiting example that can be applied to instruments and toolsdescribed herein to lower system cost and provide a performance upgradepath. Module 2210 comprises an electronic assembly 2212 for receiving,processing, and sending measurement data from sensors in the sensoredhead of spinal instrument 2202. Electronic assembly 2212 corresponds toelectronic assembly 2024 of FIG. 15 and includes at least some of thecircuitry described in FIG. 11 and FIG. 12. Electronic assembly 2212 issealed within module 2210 and is isolated from an external environment.Module 2210 couples to and is removable from spinal instrument 2202. Ingeneral, spinal instrument 2202 includes an electrical interface thatcouples to module 2210. In the example, spinal instrument 2202 includesa cavity 2214 for receiving module 2210. An electrical interface 2308 incavity 2214 couples to and aligns with electrical interface 2302 whenmodule 2210 is inserted. In one embodiment, electrical interfaces 2302and 2308 are held together under pressure to ensure electrical couplingof each interface. For example, electrical interface 2308 can includespring contacts that compress under insertion of module 2210 to maintaincoupling under force. A flexible interconnect 2310 couples to electricalinterface 2308 in cavity 2214 of handle 2206. Flexible interconnect 2310extends through the shaft of spinal instrument 2202 for coupling tosensors in a sensored head region of the device.

In the example, module 2210 can be made from a polymer material such aspolycarbonate. Module 2210 can be molded in two or more pieces andassemble together to form a housing or enclosure. Electronic assembly2212 can be placed in a molded cavity that retains and orients thecircuitry within module 2210. Electronic assembly 2212 can be coupled toelectrical interface 2302 using a flexible interconnect. Electronicassembly 2212 and electrical interface 2302 can include one or moreconnectors that couple to the flexible interconnect to simplifyassembly. The remaining molded pieces can be attached to form thehousing or enclosure using sealing methodologies such as adhesives,welding, mechanical fastening, or bonding. In one embodiment, wirelesscommunication is used to send measurement data from spinal instrument2202 to a remote system for display and visualization. A polymermaterial such as polycarbonate is transmissive to wireless signalsallowing the measurement data to be transmitted from within module 2210through the enclosure.

Module 2210 further includes a feature 2304 to align and retain thedevice when coupled to spinal instrument 2202. Feature 2304 fits intoopening 2312 when module 2210 is inserting into cavity 2214 of handle2206. A locking mechanism is shown in an opposing view of module 2210.The locking mechanism comprises a flexible tab 2306 having a flange 2316that extends from tab 2306. Flange 2316 corresponds and fits intoopening 2314 in cavity 2214 of handle 2206. The features 2304 and 2316respectively in openings 2312 and 2314 retain and prevent module 2210from disengaging during use of spinal instrument 2202. A removal processof module 2210 requires flexible tab 2306 to be flexed such that flange2316 is removed from opening 2214. Module 2210 can then be disengagedfrom cavity 2214 while bending flexible tab 2306 to prevent flange 2316from coupling to opening 2314.

FIG. 19 illustrates a shaft 2404 for receiving a removable sensored head2402 in accordance with an example embodiment. The illustration shows adetailed view of sensored head 2402 and a distal end 2404 of shaft 2208of FIG. 17. Reference can be made to components of FIG. 17 and FIG. 18.Sensored head 2402 corresponds to sensored heads 2204A-F of FIG. 17 forproviding an example of a removable sensored head from spinal instrument2202. In general, a proximal end of sensored head 2402 includes acoupling that mates with a coupling on the distal end 2404 of shaft 2208of the tool. The couplings mate together to physically attach sensoredhead 2402 and shaft 2208 for a distraction and measurement process. Thecoupling on the proximal end of sensored head 2402 and the coupling ondistal end 2404 of shaft 2208 when attached form a rigid structure thatcan be inserted in the spinal region and moved to position the deviceunder load. Sensored head 2402 includes one or more sensors formeasuring a parameter of the spinal region. The sensors can be coupledby a flexible interconnect within sensored head 2402 to an electricalinterface in proximity to the coupling on sensored head 2402. Similarly,an electronic assembly can be coupled to an electrical interface on thedistal end 2404 of shaft 2208 by a flexible interconnect that extendsthrough a lengthwise passage of shaft 2208. The electrical interfaces ofsensored head 2402 and distal end 2404 of shaft 2208 align and couplethe electrical assembly to the sensors when attached together by thecouplings. Thus, sensored head 2402 can be removed and replaced whenrequired during the procedure.

A female coupling is accessible through an opening 2406 at a proximalend of the sensored head 2402 in the example attachment mechanism. Amale coupling 2408 extends from distal end 2404 of shaft 2208. The malecoupling 2408 comprises a cylindrical extension 2414 having a retainingfeature 2416. The coupling types can be reversed such that the malecoupling is on sensored head 2402 and the female coupling on distal end2404 of shaft 2208. An electrical interface 2410 can be formed on thedistal end of shaft 2404. Male coupling 2408 extends centrally fromelectrical interface 2410. Electrical interface 2410 includesspring-loaded pins 2412 for electrical coupling and seals the distal end2404 of shaft 2208. Spring-loaded pins 2412 are located on a peripheryof electrical interface 2410 around male coupling 2408. Spring loadedpins 2412 couple to a flexible interconnect within shaft 2208. Springloaded pins 2412 can compress under pressure applied by the attachingprocess. The force applied by spring loaded pins 2412 to thecorresponding electrical interface on sensored head 2402 ensuresreliable electrical coupling from sensors to the electrical assemblywhen attached. Spring-loaded pins 2412 include a gasket or seal toisolate an interior of shaft 2208 from an external environment. In oneembodiment, electrical interface 2410 can be sealed allowingsterilization of shaft 2404 and handle 2206 for reuse in a subsequentprocedure. As shown, there are five spring-loaded pins 2412 onelectrical interface 2410. The five pins couple to four sensors insensored head 2402 and ground. In the example, the four sensors measureload and position of load applied by the spinal region to the exteriorsurfaces of sensored head 2402.

FIG. 20 illustrates a cross-sectional view of a female coupling 2502 ofsensored head 2402 in accordance with an example embodiment. In general,male coupling 2408 couples to female coupling 2602 to retain sensoredhead 2402 to distal end 2404 of shaft 2208. Reference may be made toFIG. 17, FIG. 18, and FIG. 19. Opening 2406 of sensored head 2402receives the distal end 2404 of shaft 2208. Female coupling 2502includes an electrical interface 2504 that corresponds to electricalinterface 2410 on distal end 2404 of shaft 2208. Electrical interface2504 includes electrical contact points 2506 that align to spring loadedpins 2412 when sensored head 2502 is attached to distal end 2404 ofshaft 2208. Electrical interconnect 2508 couples electrical contactpoints 2506 to sensors in sensored head 2402. Female coupling 2502includes a keyed opening 2510 that is located centrally on thestructure. Keyed opening 2510 has a single position that allowsretaining feature 2416 to be inserted through female coupling 2502.

In one embodiment, the outer diameter of electrical interface 2410 isapproximately equal to or smaller than the inner diameter of opening2406. The fit of electrical interface 2410 to opening 2406 supports therigid coupling of sensored head 2402 to shaft 2404. Sensored head 2402is rotated after retaining feature 2416 is inserted through keyedopening 2510. A spring-loaded barrier 2512 is in a rotation path ofretaining feature 2416. Spring-loaded barrier 2512 can compress toapproximately surface level of the surface of female coupling 2502. Thesurface of spring-loaded barrier 2512 can be curved or spherical.Retaining feature 2416 when rotated compresses spring-loaded barrier2512 and rotates over the structure during the attaching process. Thespring in spring loaded barrier 2512 raises the structure back above thesurface of female coupling 2502 after retaining feature rotates past. Arotation stop 2514 in the rotation path prevents further rotation ofsensored head 2402 by blocking retaining feature 2416.

In one embodiment, retaining feature 2416 is stopped between rotationstop 2514 and spring-loaded barrier 2512. Rotation stop 2514 and springloaded barrier 2512 form a barrier to prevent movement and rotation ofsensored head 2402 when in use. Furthermore, rotation stop 2514positions sensored head 2402 such that electrical interface 2504 andelectrical interface 2410 are aligned for coupling sensors in sensoredhead 2402 to the electrical assembly for providing sensor measurementdata. In general, retaining feature 2416 is held against the surface offemale coupling 2502 under force. For example, the rotation path ofretaining feature 2416 can be sloped to increase the force betweenretaining feature 2416 and the surface of female coupling 2502 as itapproaches rotation stop 2514. Spring loaded pins 2412 can also apply aforce that presses retaining feature 2416 to the surface of femalecoupling 2502.

FIG. 21 illustrates an exploded view of a spinal instrument 2600 inaccordance with an example embodiment. Spinal instrument 2600 is a moredetailed illustration of a non-limiting example of spinal instrument 102of FIG. 1, spinal instrument 400 of FIG. 2, and spinal instrument 410 ofFIG. 3. Spinal instrument 2600 is a measurement device having a sensoredhead 2002 that incorporates at least one sensor for measuring aparameter of a spinal region. Spinal instrument 2600 comprises a housing2602, housing 2604, electronic assembly 2626, interconnect 2630, andsensors 2638. In general, housings 2602 and 2604 couple together toisolate electronic assembly 2626, interconnect 2630, and sensors 2638from an external environment. Housings 2602 and 2604 respectivelyinclude a support structure 2610 and a support structure 2616. Sensors2638 couple to support structures 2610 and 2616 to measure the parameterof the spinal region. In a surgical procedure, support structures 2610and 2616 can come in contact with the spinal region. In one embodiment,support structures 2610 and 2616 comprise a sensored head of spinalinstrument 2600 that can compress sensors 2638 when a compressive forceis applied.

Housing 2602 comprises a handle portion 2606, a shaft portion 2608, andthe support structure 2610. Similarly, housing 2604 comprises a handleportion 2612, a shaft portion 2614, and the support structure 2616.Housing 2604 further includes a flange 2644, a cavity 2618, and alengthwise passage 2646. Flange 2644 is a reinforced structure on aproximal end of the handle of spinal instrument 2600. Flange 2644 can bestruck with a hammer or mallet to provide an impact force to insert thesensored head of spinal instrument 2600 into the spinal region. Cavity2618 supports and retains an electronic assembly 2626. Electronicassembly 2626 receives, processes, and sends quantitative measurementsfrom sensors 2638. A power source 2628 couples to electronic assembly2626. In one embodiment, the power source can be one or more batteriesthat are mounted on a printed circuit board of electronic assembly 2626.Electronic assembly 2626 can be coupled to sensors 2638 by a flexibleinterconnect 2630. Flexible interconnect 2630 can comprise a flexiblesubstrate having patterned electrically conductive metal traces.Electronic assembly 2626 can have one or more connectors that couple toflexible interconnect 2630 to simplify assembly. Flexible interconnect2630 couples through a lengthwise passage in the shaft of spinalinstrument 2600. In one embodiment, lengthwise passage 2646 is used as achannel for flexible interconnect 2630 that couples cavity 2618 to asensored head region. Retaining features 2640 can retain power source2628, electronic assembly 2626, and flexible interconnect 2630 in placewhen assembling spinal instrument 2600. Retaining features 2640 cancomprise foam that can be coupled to components and compress withoutdamaging active components as housing 2602 is coupled to housing 2604.

The sensored head of spinal instrument 2600 comprises support structure2610, support structure 2616, interconnect 2634, sensor guide 2636, andsensors 2638. The exterior surfaces of support structures 2610 and 2616may be shaped convex to support insertion into the spinal region.Interconnect 2634 is a portion of flexible interconnect 2630 thatoverlies an interior surface of support structure 2616. Flexibleinterconnect 2634 includes conductive traces that couple to electricalcontact regions of sensors 2638. Sensor guide 2636 overlies interconnect2634. In one embodiment, interconnect 2634 and sensor guide 2636 can bealigned and retained within support structure 2616 by a peripheralsidewall. Sensor guide 2636 includes openings for retaining andpositioning sensors 2638. In the example, sensors 2638 are force,pressure, or load sensors. Interconnect 2634 can have electrical contactregions that align with the openings of sensor guide 2636. Theelectrical contact regions are exposed for coupling to sensors 2638through the openings of sensor guide 2636. Sensor guide 2636 alsoretains and positions sensors 2638 such that the electrical interface ofeach sensor can couple to a corresponding electrical contact region ofinterconnect 2634. The electrical interface of sensors 2638 can becoupled to the corresponding electrical contact region of interconnect2634 by such means as solder, conductive epoxy, eutectic bond,ultrasonic bond, or mechanical coupling. Sensor guide 2636 alsopositions sensors to couple to support structure 2610 or 2616 atpredetermined locations. In one embodiment, sensors 2638 contact aninternal surface of support structure 2610 or 2616 that correspond tolocations on the external surfaces. Positioning the sensors via sensorguide 2636 allows the position of the applied load on the externalsurface of support structure 2610 to be calculated. A load plate 2642can be coupled between sensors 2638 and the interior surface of supportstructure 2610. Load plate 2642 distributes loading from the interiorsurface of support structure 2610 to each sensor 2638.

As mentioned previously, housings 2602 and 2604 when coupled togethersupport compression of the sensored head of spinal instrument 2600. Acompressive force applied across the external surfaces of supportstructures 2610 and 2616 is directed to sensors 2638. Other componentssuch as support structure 2610, support structure 2616, load plate 2642,and interconnect 2634 in the compression path do not deform under load.In one embodiment, load plate 2642 comprises a metal such as steel orstainless steel. A compressible adhesive 2624 can be used to couple theperiphery of support structures 2610 and 2616 thereby allowing movementof the sensored head and sensors 2638 therein over the measurementrange. The compressible adhesive 2624 can be an adhesive such as asilicone based adhesive. The adhesive 2624 is elastic such that thesensored head returns to an unloaded position or moves to a repeatableunloaded height after being compressed. In one embodiment, a secondadhesive 2622 is used around a remaining periphery of housings 2602 and2604 to seal and couple the structures together. Adhesives 2622 and 2624are applied prior to coupling housings 2602 and 2604 together. Adhesive2622 can be a bonding adhesive such as a glue or epoxy that mates theperipheral surfaces together. In other words, the bonded surfacescoupled by adhesive 2622 do not have a range of compression as thesurfaces are held in contact to one another by adhesive 2622.Alternatively, adhesive 2624 can be used around the entire periphery tocouple housings 2602 and 2604 together.

FIG. 22 illustrates a cross-sectional view of a shaft region of spinalinstrument 2600 in accordance with an example embodiment. The shaftregion is a cross-sectional view comprising shaft 2608 and 2614respectively of housing 2602 and housing 2604 coupled together. Theillustration provides detail on the coupling of housings 2602 and 2604that corresponds a portion of the shaft region and a handle region ofspinal instrument 2600. Reference can be made to components of FIG. 21.In general, a housing for the active components of spinal instrument2600 is formed by coupling housing 2602 to housing 2604. In oneembodiment, peripheral surfaces of housing 2602 and housing 2604 arefastened together using more than one adhesive. The peripheral surfacesof housings 2602 and housing 2604 mate such that the structures align,form a barrier, and provide surface area for bonding. In the example, aperipheral surface 2702 of housing 2602 has a geometric shape such as atriangular extension. A peripheral surface 2704 of housing 2604 has acorresponding geometric shape such as a v-shaped groove for receivingthe triangular extension. Other tongue and groove geometry can be usedsuch as square, round, or other polygonal shapes. Joints such as abutt-joint or a lap joint can also be used. The profile of theperipheral surfaces of a sensored head region differs from peripheralsurfaces 2702 and 2704 of the shaft and handle regions. In the example,surfaces of the triangular extension of peripheral surface 2702 contactsurfaces of the v-shaped groove of peripheral surface 2704 when housings2602 and 2604 are coupled together.

As mentioned previously, peripheral surfaces 2702 and 2704 respectivelyof housings 2602 and 2604 couple the handle portion and the shaftportion of spinal instrument 2600. Peripheral surface 2702 fits intoperipheral surface 2704 providing alignment feedback during assembly.Referring to FIG. 21, the handle portion and the shaft portioncorresponds to the area where adhesive 2622 are applied. In the example,adhesive 2622 attaches or bonds peripheral surfaces 2702 and 2704together with no play or gap between the surfaces other than theadhesive material. In one embodiment, the handle portion and the shaftportion coupled by peripheral surfaces 2702 and 2704 cannot bedisassembled without damage to the housing due to the bond integrity ofthe joint. The shape of peripheral surfaces 2702 and adhesive 2622 sealsand isolates an interior of spinal instrument 2600 from an externalenvironment. As shown, a portion of the distal end of the shaft and theperipheral surfaces of support structures 2610 and 2616 can have adifferent profile as disclosed herein. Similarly, other geometric shapedsurfaces or curved surfaces can be used for peripheral surfaces 2702 and2704.

FIG. 23 illustrates a cross-sectional view of a sensored head region ofspinal instrument 2600 in accordance with an example embodiment. Theillustration provides detail on the coupling of support structures 2610and 2616 corresponding to the sensored head region and a distal portionof the shaft region. Reference can be made to components of FIG. 21 andFIG. 22. In general, the sensored head region includes at least onesensor for measuring a parameter of the spinal region. In the example,sensors for measuring a force, pressure, or load are coupled betweensupport structures 2610 and 2616. The support structures 2610 and 2616compress the sensors when inserted into the spinal region. The sensorsoutput a signal corresponding to the compression. Thus, supportstructures 2610 and 2616 move in relation to one another allowingcompression of the sensors.

As shown, the periphery of housing 2602 and housing 2604 correspondingto support structures 2610 and 2616 of the sensored head region coupletogether in a manner allowing movement. Support structure 2610 ofhousing 2602 includes a peripheral surface 2802 having a triangularshaped region. Support structure 2616 of housing 2604 includes aperipheral surface 2804 having a v-shaped groove. In one embodiment, agap 2806 exists between peripheral surface 2802 and peripheral surface2804 when housing 2602 is coupled to housing 2604. More specifically,the surfaces of the triangular shaped region of peripheral surface 2802do not contact the surfaces of the v-shaped groove of peripheral surface2804 when peripheral surface 2702 of housing 2602 contacts peripheralsurface 2704 of housing 2604 as shown in FIG. 22. Gap 2806 allows acompressive force applied to the external surfaces of support structures2610 and 2616 to move such that the height of the sensored head regionis reduced. Gap 2806 is larger than a change in height of the sensorsover the measurement range of spinal instrument 2600. Although surfacesare shown as triangular and v-groove shaped in the non-limiting example,surfaces 2802 and 2804 can take other shapes that support gap 2806 andmovement of support structures 2610 and 2616.

The sensored head region and the portion of the distal end of the shaftcorresponds to the area where adhesive 2624 shown in FIG. 21. In theexample, adhesive 2624 elastically attach peripheral surfaces 2802 and2804 together. Adhesive 2624 fills gap 2806 between the peripheralsurfaces 2802 and 2804. Support structures 2610 and 2616 form a housingfor the sensor assembly of spinal instrument 2600. Adhesive 2624 cancompress when a load is applied across support structures 2610 and 2616.Adhesive 2624 rebounds elastically after compression of the supportstructures 2610 and 2616 thereby returning the sensored head region backto gap 2806 when unloaded. Filling gap 2806 with adhesive 2624 seals andisolates an interior of the sensored head region and the distal end ofthe shaft from an external environment. In one embodiment, adhesive 2622and adhesive 2624 are applied at approximately the same time during theassembly process. Adhesive 2622 is applied to at least one of peripheralsurfaces 2702 and 2704 of FIG. 22. Similarly, adhesive 2624 is appliedto at least one of peripheral surfaces 2802 and 2804. Housing 2602 andhousing 2604 are then coupled together to form the housing for theactive system of spinal instrument 2600.

In one embodiment, support structure 2610 and support structure 2616 canbe modified to make the exterior load bearing surfaces flexible. Aperipheral groove 3006 is formed in the support structure 2610. Ingeneral the groove is formed circumferentially such that the externalload-bearing surface can flex. A force, pressure, or load is directed tosensors underlying the load bearing surface. The flexible supportstructure load-bearing surface minimizes load coupling that can causemeasurement error. For example, grooves 3006 reduce load coupling fromperipheral surface 2802 to 2804. Loading applied to the load-bearingsurface of support structure 2610 is coupled through interior surface3004 to load sensors 2638. Grooves 3006 can bound interior surface 3004.A load plate can be used to distribute loading from internal surface3004 to sensors 2636. Similarly, a groove 3008 is formedcircumferentially in support structure 2616 such that the externalload-bearing surface of support structure 2616 can flex. A force,pressure, or load applied to the load-bearing surface of supportstructure 2616 is directed through interior surface 3002 to sensors2638. The load coupling through surface 2804 to surface 2802 isminimized by the flexible external load-bearing surface of supportstructure 2616. Grooves 3008 can bound interior surface 3002.

FIG. 24 illustrates an exploded view of a sensored head region of spinalinstrument 2600 in accordance with an example embodiment. In general,support structure 2616 includes a sidewall 2904 having peripheralsurface 2804. As shown, the peripheral surface 2804 of sidewall 2904 isa v-groove. Interconnect 2634 of flexible interconnect 2634 couplessensors 2638 to electronic assembly 2626. Flexible interconnect 2634extends through the shaft of spinal instrument 2600 to the sensored headregion. In one embodiment, interconnect 2634 can be shaped to fit insupport structure 2616. Interconnect 2634 overlies an interior surfaceof support structure 2616. Interconnect 2634 is positioned, aligned, andretained on support structure 2616 by sidewalls 2904.

As shown, sensor guide 2636 overlies interconnect 2634. Sensor guide2636 positions and holds sensors 2838. In one embodiment, sensor guideincludes openings 2906 for four sensors. The four sensors 2838 candetermine a load magnitude applied to support structures 2610 and 2616as well as position of the applied load. Electrical contacts of sensor2638 couple to corresponding contact regions on interconnect 2634. Inone embodiment, each sensor 2638 has two contacts, one of which is acommon ground. Openings 2906 of sensor guide 2636 align to and exposethe underlying interconnect 2634. Moreover, openings 2906 show contactregions of interconnect 2634 for coupling to a sensor. A load plate 2636can overlie sensors 2638. Load plate 2636 is an optional component fordistributing an applied force, load, or pressure applied to supportstructures 2610 and 2616 to sensors 2638. Load plate 2636 couples to aninterior surface of support structure 2610. Load plate 2636 can also bepositioned and aligned in the sensored head region by sidewalls 2904 ofsupport structure 2616. Alternatively, support structure 2610 can have aretaining feature for load plate 2636.

FIG. 25 illustrates a cross-sectional view of an assembled sensored headregion of spinal instrument 2600 in accordance with an exampleembodiment. The illustration provides detail on the stacked assemblywithin support structures 2610 and 2616 corresponding to the sensoredhead region. Reference can be made to components of FIG. 21, FIG. 23,and FIG. 24. Support structure 2616 includes sidewall 2904 that boundsinterior surface 3002. In the example, groove 3008 is adjacent tosidewall 2904 and bounds surface 3002 of support structure 2616. Groove3008 promotes support structure 2616 to flex under loading. Flexibleinterconnect 2630 couples electronic assembly 2626 to sensors 2638.Flexible interconnect 2630 includes interconnect 2634 that is housed inthe sensored head region of spinal instrument 2600. Interconnect 2634includes contact regions for coupling to sensors 2638. Interconnect 2634overlies interior surface 3002 of support structure 2616. Interconnect2634 is retained, aligned, and positioned within the sensored headregion by sidewall 3002 of support structure 2616.

Sensor guide 2636 overlies interconnect 2634. Sensor guide 2636 isshaped similar to interconnect 2634. Sensor guide 2636 is retained,aligned, and positioned within the sensored head region by sidewall 2904of support structure 2616. Sensor guide 2636 has openings that alignwith the contact regions of interconnect 2634. Sensors 2638 are placedin the openings of sensor guide 2636 such that contacts of sensors 2638couple to contact regions on interconnect 2634. In one embodiment,sensor guide plate 2636 comprises a non-conductive polymer material. Inthe example, sensors 2638 extend above a surface of sensor guide 2636for coupling to load plate 2642 or an interior surface of supportstructure 2610.

A load plate 2642 is an optional component of the stacked assembly. Loadplate 2642 distributes the force, pressure, or load applied to supportstructures 2610 and 2616 to sensors 2638. In one embodiment, load plate2642 can be shaped similarly to interconnect 2634 and sensor guide 2634.Load plate 2642 overlies and couples to sensors 2638. In the example,support structure 2610 includes a peripheral sidewall that positionsload plate 2642 over sensors 2638. In the example, groove 3006 isadjacent to the peripheral sidewall of support structure 2610 and boundssurface 3004 of support structure 2610. Groove 3006 promotes supportstructure 2610 to flex under loading. An internal surface 3004 ofsupport structure 2610 couples to load plate 2642. Peripheral surface2802 of support structure 2610 is coupled to peripheral surface 2804 ofsupport structure 2616 in a manner to support movement under acompressive load. In particular, sensors 2638 can change in height underloading. As disclosed above, elastic adhesive 2624 fills a gap betweenperipheral surfaces 2802 and 2804. Adhesive 2624 couples supportstructures 2610 and 2616 together. The adhesive 2624 seals and isolatesthe stacked assembly of the sensored head region from an externalenvironment. Moreover, adhesive 2624 can compress such that a force,pressure, or load applied to support structures 2610 and 2616 translatesfrom the external surfaces to sensors 2638 for measurement.

FIG. 26 illustrates a spinal instrument 3100 and a cradle 3108 inaccordance with an example embodiment. In general, spinal instrument3100 is an orthopedic tool including one or more sensors for measuring aparameter of the spinal region. In one embodiment, spinal instrument3100 is a disposable device. For example, spinal instrument 3100 used ina surgical procedure would be disposed of after the surgery iscompleted. As a safe guard, a non-removable power source within spinalinstrument 3100 may not have sufficient charge for more than a singleprocedure. A further safeguard to prevent reuse of spinal instrument3100 is to allow the end user to enable the device but prevent thedevice from being disabled or turned off. In general, the power sourceof spinal instrument 3100 will continue to discharge after themeasurement process has been completed with the device remaining on. Inone embodiment, the voltage of the internal power source will eventuallydecline due to current drain from the electronics thereby causing adevice shutdown for a low voltage condition. It should be noted that theenable and disable process is applicable for electronic medical devicesand more specifically for disposable medical devices such as orthopedicprosthetic components, measurement equipment and electronic tools.

Spinal instrument 3100 includes an electronic assembly 3104 that iscoupled to one or more sensors. A power source 3114 such as a battery orcapacitor can be mounted on electronic assembly 3104. As shown, theelectronic assembly 3104 can be placed in a main body or handle sectionof the device. In one embodiment, electronic assembly 3104 is sealed inthe handle of spinal instrument 3100 and cannot be removed. An indicator3102 can provide a visual, audible, or haptic indication of a power onsequence or enablement status. In one embodiment, indicator 3102 can bea light emitting diode. Electronic assembly 3104 further includes amagnetic sensitive switch 3106 to detect when spinal instrument 3100 isin the presence of a magnetic field above a threshold value. Magneticsensitive switch 3106 couples to electronic circuitry on electronicassembly 3104 to enable and disable spinal instrument 3100.

Cradle 3108 supports spinal instrument 3100 to enable the spinalinstrument 3100. Typically, cradle 3108 is used by the end user such asa surgeon, doctor, or health care provider. In the example, spinalinstrument 3100 can be used in an operating room for a surgicalprocedure. Cradle 3108 is located in proximity to where the spinalinstrument 3100 is used. Cradle 3108 is formed to support, hold, andposition spinal instrument 3100. Spinal instrument 3100 can be easilyremoved from cradle 3108. In one embodiment, spinal instrument 3100 canbe placed in a molded cavity 3112 to position and enable the device.Cradle 3108 includes a magnet 3110 underlying cavity 3112. Placingspinal instrument 3100 in cradle 3108 exposes magnetic sensitive switch3106 to a magnetic field from magnet 3110. The magnetic field generatedby magnet 3110 is greater than the threshold value of magnetic sensitiveswitch 3106 when placed in cavity 3112 thereby causing magneticsensitive switch 3106 to change state. For example, if magneticsensitive switch 3106 is normally open then placing spinal instrument3100 in cradle 3108 will close the switch. Conversely, removing spinalinstrument 3100 from cradle 3112 reduces the magnetic field below thethreshold value such that the magnetic sensitive switch is open. Thetiming of the opening and closing of magnetic sensitive switch 3108generates a signal that is received by circuitry of the electronicassembly 3104 to enable and disable spinal instrument 3100. In oneembodiment, the power source can be physically decoupled from theelectronic circuitry. The circuitry and process for enabling a medicaldevice is disclosed in more detail below.

FIG. 27 illustrates a knee insert 3200 and a cradle 3208 in accordancewith an example embodiment. The example illustrates another type ofmedical device that can be enabled and disabled by placement within amagnetic field as disclosed in FIG. 26. Knee insert 3200 is a prostheticcomponent having at least one articular surface for allowingarticulation of a knee joint. As shown, knee insert 3200 has twoarticular surfaces. Knee insert 3200 can be used intra-operatively orpermanently in the knee to provide measurement data. Although a kneeinsert is shown, the circuit and method described in detail below can beused for other prosthetic components having sensors for measurement ofparameters of the human body and more specifically to themuscular-skeletal system such as joints, bones, tendons, ligaments, andmuscle.

Insert 3200 includes one or more sensors for measuring a parameter ofthe muscular-skeletal system. In one embodiment, insert 3200 includespressure sensors coupled to the articular surfaces for measuring a loadmagnitude and position of load applied. Insert 3200 includes anelectronic assembly 3204 coupled to the pressure sensors for receivingand sending measurement data. Electronic assembly 3204 can comprise aprinted circuit board, a power source, electrical components, and anASIC. Electronic assembly 3204 is housed in insert 3200. An indicator3202 provides an enable or disable status of electronic assembly 3204.It can also indicate a startup process of knee insert 3200 inpreparation for measuring parameters. A magnetic sensitive switch 3206is located on electronic assembly 3204 for detecting a magnetic fieldabove a threshold value. Detection of the magnetic field is used toinitiate enabling or disabling electronic assembly 3204 of knee insert3200.

Similar to cradle 3108 of FIG. 26, cradle 3208 can be used to enableknee insert 3200. Cradle 3208 includes a cavity 3212 for knee insert3200. A magnet 3210 underlies cavity 3212. In one embodiment, cavity3212 is shaped to fit knee insert 3200 thereby placing magneticsensitive switch 3206 in alignment and proximity to magnet 3210. Placingknee insert 3200 in cradle 3208 initiates an enabling process whenmagnetic sensitive switch 3206 changes state due to the magnetic fieldof magnet 3210. In one embodiment, knee insert 3200 is enabled andcannot be disabled after being placed in cradle 3208 for longer than apredetermined time. Alternatively, knee insert 3200 can be enabled in amode that allows disabling by removing knee insert 3200 from cradle 3208before the predetermined time period. Knee insert 3200 can be easilyremoved by hand from cradle 3208 after being enabled. The timingsequence and circuitry for enabling and disabling a medical device isdescribed in more detail below.

FIG. 28 illustrates a block diagram of a system 3300 to enable anddisable a medical 3304 device in accordance with an example embodiment.The system 3300 and method of operation is applicable to a broad rangeof medical devices such as the spinal instrument and prostheticcomponent respectively of FIG. 26 and FIG. 27. In general, system 3300has a first mode of operation where the device is enabled and can beturned off at a time of the users choosing. A second mode of operationhas the device enabled and cannot be turned off. The spinal instrumentdisclosed herein is used as an example to illustrate the advantages of aproximity enabling and disabling methodology.

System 3300 comprises a medical device 3304 and a cradle 3306. Themedical device 3304 is enabled and disabled by a magnetic field 3310. Ina non-limiting example, a magnet 3308 can generate magnetic field 3310.Magnet 3308 can be placed in cradle 3306. Cradle 3306 can be designed tohold and position a predetermined area of medical device 3304 to be inproximity to magnet 3308. A magnetic sensitive switch 3318 resides inthe predetermined area of medical device 3304. Medical device 3304 incradle 3306 exposes magnetic sensitive switch 3318 to magnetic field3310 that is greater than a threshold value. Placing magnetic sensitiveswitch 3318 in the cradle changes a state of the switch. For example,magnetic sensitive switch 3318 can be normally open. Exposing magneticsensitive switch 3318 to a magnetic field greater than the thresholdvalue closes the switch. Magnetic sensitive switch 3318 remains closeduntil the magnetic field falls below the threshold value. The magneticsensitive switch 3318 returns to an open state when the medical device3304 is removed from cradle 3306 causing magnetic field 3310 to fallbelow the threshold value.

The medical device 3304 includes a power source 3312, a switch 3314,electronic circuitry 3316, an indicator 3326, magnetic sensitive switch3318, detect circuit 3320, delay circuit 3322, and logic circuitry 3324.In the example of a spinal instrument as medical device 3304 thecomponents listed above would be housed within the spinal instrument.The spinal instrument may be used in a surgical procedure to aid in theinstallation of a prosthetic component. The cradle 3306, typically wouldreside in proximity to or in an operating room 3302 that would allow thesurgeon or staff to enable the instrument for generating quantitativemeasurements of the spinal region. The spinal instrument can be a singleuse device that is disposed of after the surgical procedure. Powersource 3312 has sufficient power for the single application. The spinalinstrument would be operated in the second mode as disclosed above.Operation in the second mode prevents further use of the medical device3304 as the internal power source 3312 will eventually discharge makingelectronic circuitry 3316 inoperable.

Magnetic sensitive switch 3318 is a device that changes state in thepresence of a magnetic field. Non-limiting examples of magneticsensitive switch 3318 are a reed switch or a hall-effect device.Magnetic sensitive switch 3318 can be normally open. Magnetic sensitiveswitch 3318 couples to detect circuit 3320. Detect circuit 3320 convertsan open or closed condition of switch 3318 respectively into a detect=1or detect=0 state for switch 3318 normally open (e.g. no magnetic fieldpresent). In one embodiment, detect circuit 3320 can be an inverterhaving an input coupled to ground through a resistor. Switch 3318 in anopen state (e.g. no magnetic field) would not affect the input of detectcircuit 3320. The detect circuit 3320 would output a detect=1 state withswitch 3318 in the open state. Switch 3318 in the presence of magneticfield 3310 changes from an open state to a closed state. Switch 3318 cancouple a voltage to the input of detect circuit 3320. As mentionedpreviously, the detect circuit 3320 comprises an inverter. The voltageprovided to the input of switch 3318 transitions the output of detectcircuit 3320 from the detect=1 state to a detect=0 state to initiate anenable process of medical device 3304.

Detect circuit 3320 couples to delay circuit 3322. Delay circuit 3322generates a first delay D1 of a first predetermined time period and asecond delay D2 of a second predetermined time period when medicaldevice 3304 is in the presence of magnetic field 3310. Second delay D2is longer than first delay D1. Delay circuit 3322 can be triggered whenthe output of detect circuit 3320 changes from the detect=1 state to thedetect=0 state. Delay circuit 3322 couples to logic circuitry 3324. Ingeneral, the first delay and second delays create three distinct timeperiods. A first time period corresponds to the time when detect=0 tothe first delay D1. The second time period corresponds to the time forthe first delay D1 to the second delay D2. The third time periodcorresponds to the time after the second delay D2.

In general, medical device 3304 is enabled during the first, second, andthird time periods that is initiated when detect circuit 3320transitions from detect=1 to a detect=0 state. In one embodiment,medical device 3304 can be disabled during the first and second timeperiods. Switch 3314 couples power source 3312 to electronic circuitry3316 when medical device 3304 is enabled. A control signal to switch3314 is provided by logic circuitry 3324. In the spinal instrumentexample, power source 3312 is internal to the instrument and comprisesone or more batteries. The batteries cannot be removed, replaced, orcharged after being discharged. Thus, the batteries provide power for asingle application and the spinal instrument is disposed of after beingused.

The first time period generated by delay circuit 3322 is of sufficientlength to ensure that the medical device 3304 does not turn on due tobeing placed in a transient magnetic field. In one embodiment, the firsttime period is approximately 0.5 seconds. Medical device 3304 isdisabled if magnetic field 3310 falls below the threshold value beforethe first time period expires. As mentioned previously, during the firsttime period power source 3312 is coupled to electronic circuitry 3312 byswitch 3314. Logic circuitry 3324 enables switch 3314 and initiates astartup procedure for electronic circuitry 3312 of medical device 3304.Logic circuitry 3324 enables indicator 3326 to indicate that medicaldevice 3304 is powered. Indicator 3326 can provide visual, audio, orhaptic indication of medical device 3304 being powered. In oneembodiment, indicator 3326 is a light emitting diode that emits lightduring the first time period. In general, the startup procedure cancomprise a power on reset and calibration of medical device 3304 inpreparation for being used. The user would be notified should an erroror problem be identified during the startup procedure. In oneembodiment, medical device 3304 cannot take measurements the during thefirst time period. The magnetic field 3310 falling below the thresholdvalue during the first time period is detected by detect circuit 3320thereby generating a detect=1 state. The detect=1 state during the firsttime period causes logic circuitry 3324 to generate a control signal todecouple power source 3312 from electronic circuitry 3316. The startupprocedure is interrupted and medical device 3304 is shut down by thedetect=1 state during the first time period. Indicator 3326 is disabledby logic circuitry 3324 indicating that electronic circuitry 3316 is nolonger powered. In the example, the light emitting diode would no longeremit light.

The second time period corresponds to the time between delay D1 anddelay D2 generated by delay circuit 3322 during which detect circuit3320 remains in a detect=0 state. In one embodiment, the power on resetand calibration of medical device 3304 is completed prior to the end ofthe first time period. In the second time period, medical device 3304can be placed in a first mode of operation that allows power source 3312to be decoupled from electronic circuitry 3316 at a time of the userschoosing. Medical device 3304 can be placed in the first mode ofoperation by generating a detect=1 state during the second time period.The detect=1 state can be generated by removing medical device 3304 fromcradle 3306 such that magnetic field 3310 falls below the thresholdvalue before the end of delay D2. The window of time between delay D1and delay D2 is such that the operational state can be easily initiated.In one embodiment, delay D1 is 0.5 seconds and delay D2 is 3.0 seconds.The window of time to remove medical device 3304 from cradle 3306 toinitiate the second mode of operation is 2.5 seconds. Detect circuit3320 detects the change in magnetic field 3310 and transitions from thedetect=0 state to a detect=1 state. Logic circuitry 3324 maintainsswitch 3314 enabled for powering electronic circuitry 3316 uponreceiving the detect=1 state. Indicator 3326 continues to indicate thatpower supply 3312 is coupled to electronic circuitry 3316. In the spinalinstrument example, the first operational state can be utilized by themanufacturer to test and calibrate the device after it has beenassembled. Furthermore, the spinal instrument can be sterilized and insterile packaging when enabled since it is proximity enabled anddisabled. This can be useful to test or calibrate the device prior toshipping the device. Thus, the spinal instrument may be enabled,operated, and disabled while maintaining the device in a sterilecondition. The spinal instrument operated in the first mode of operationwould be disabled to maintain sufficient charge in the internal powersource for a procedure.

Medical device 3304 can then be disabled by placing magnetic sensitiveswitch 3318 in magnetic field 3310 greater than the threshold value. Forexample, placing medical device 3304 back in cradle 3306 during thefirst mode of operation would disable the instrument. In the presence ofmagnetic field 3310 detect circuit transitions from the detect=1 stateto a detect=0 state. Typically, medical device 3304 has been enabled fora period of time greater than delay D2 in the first operational state.Logic circuitry 3324 disables switch 3314 upon receiving the detect=0state. Switch 3314 is disabled by logic circuitry 3324 therebydecoupling power source 3312 from electronic circuitry 3316. Medicaldevice 3304 may go through a sequenced shut down before switch 3314 isthe power source is decoupled. Indicator 3326 indicates that powersource 3312 is decoupled and medical device 3304 is off. Decouplingpower source 3312 from electronic circuitry 3316 reduces leakagecurrents that can discharge power source 3312 thereby increasing theshelf life of the product.

The third time period corresponds to the time period greater than thedelay D2. In one embodiment, the second mode of operation occurs whendetect circuit 3320 has maintained a detect=0 state for a period longerthan delay D2. For example, medical device 3304 is placed in cradle 3306for a time period greater than 3 seconds (D2=3 seconds). In the secondmode of operation, medical device 3304 is enabled and cannot bedisabled. Typically, the second mode of operation corresponds to an enduser using medical device 3304. In the spinal instrument example, thesurgeon has removed the device from sterile packaging and is enablingthe device for the surgical procedure such as a spinal cageinstallation. In the second mode of operation, medical device 3304remains enabled and power source 3312 cannot be decoupled fromelectronic circuitry 3316. Subsequent changes in the state of magneticsensitive switch 3318 are ignored after entering the second mode ofoperation. Thus, stray magnetic fields within an operating room do notaffect the spinal instrument even if they produce a change of state inmagnetic sensitive switch 3318. Logic circuitry 3324 maintains switch3314 enabled keeping power source 3312 coupled to electronic circuitry3316. In one embodiment, indicator 3326 that indicated power beingsupplied to electronic circuitry 3316 in the first and second timeperiod goes off in the third time period. This indication sequenceprovided by indicator 3326 indicates that medical device is enabled andcan no longer be turned off. Medical device 3304 can be used until powersource 3312 can no longer adequately power electronic circuitry 3316. Inthe spinal instrument example, medical device 3304 is used for a singleapplication and disposed of after the procedure. Maintaining switch 3314enabled will continue to drain power source 3312 since the user cannotturn off the device in the second mode of operation. Furthermore, logiccircuitry 3324 includes a circuit to monitor the voltage of power source3312. Logic circuitry 3324 detects when a low voltage condition occursand initiates shut down of medical device 3304 thereby making the devicenon-operational. Shut down of medical device 3304 under a low voltagecondition prevents further use before erroneous results can begenerated.

FIG. 29 illustrates a state diagram 3400 of a medical device enablingcircuit in accordance with an example embodiment. In general, theenabling circuit couples an internal power source to electroniccircuitry to start the operation of the medical device. In a first modeof operation the medical device is enabled when a signal is detected.The medical device can be disabled during the first mode. The first modeof operation supports testing or calibration of the medical device usingthe internal power source. The medical device can be turned off in thefirst mode operation. In one embodiment, the power source is decoupledfrom the electronic circuitry when the medical device is turned off.Decoupling the power source from the electronic circuitry maximizesshelf life and prevents discharge.

In a second mode of operation the power source cannot be decoupled fromthe electronic circuitry of the medical device after being enabled. Thesecond mode supports a single use of the medical device. Morespecifically, the power source may provide sufficient charge for only asingle use, procedure, or operation. Subsequent usage of the medicaldevice beyond its specified life cycle would likely fail beforecompletion of a measurement process due to low voltage (e.g.insufficient charge). The power source can be sealed in the medicaldevice in a manner that prevents replacement or charging. In the secondmode of operation, the power source remains coupled to the electroniccircuitry whereby the power source continues to discharge after beingused. The power source eventually discharges to a point where an undervoltage condition is detected that shuts down the device thereby makingit unusable. In the example, the medical device can be disposed of in aprocess that meets health requirements and permanently prevents reuse(e.g. destroying the medical device).

The state diagram 3400 illustrates four states where a switch can coupleor decouple a power source from electronic circuitry in a medicaldevice. A light emitting diode can be used as an indicator to the stateof the medical device. A first state 3402 comprises a condition wherethe switch is disabled such that the power source of the medical deviceis decoupled from the electronic circuitry of the medical device. Themedical device is off in first state 3402. In the example, the medicaldevice has a magnetic sensitive switch. The magnetic sensitive switch isused to detect a presence of a magnetic field. The magnetic sensitiveswitch couples to a detect circuit that generates a detect condition. Inone embodiment, the magnetic sensitive switch is normally open. Thiscorresponds to the detect circuit generating a detect=1 condition whenno magnetic field is present. The detect=1 condition disables the switchcoupling the power source to the electronic circuitry. Conversely, thedetect circuit generates a detect=0 condition when the magneticsensitive switch is closed in the presence of a magnetic field above athreshold value. The detect=0 condition enables the switch coupling thepower source to the electronic circuitry. The light emitting diode isoff in first state 3402 indicating that the medical device is notenabled. As illustrated by transition 3404 of state diagram 3400, themedical device remains in first state 3402 when no magnetic field ispresent or the magnetic field is lower than the threshold value. Thus,the power source remains decoupled from the electronic circuitry and themedical device remains off as long as no magnetic field is detected.

A transition 3408 occurs when the magnetic sensitive switch is in apresence of a magnetic field above the threshold value. The magneticsensitive switch is closed by the magnetic field. In state diagram 3400,transition 3408 transitions to a second state 3406 when the magneticsensitive switch is in the presence of a magnetic field greater than thethreshold value. The detect circuit responds to the closed magneticsensitive switch by generating the detect=0 condition. The detect=0condition enables the switch coupling the power source to the electroniccircuitry. The electronic circuitry of the medical device is enabled insecond state 3406. The light emitting diode is turned on therebyemitting light to indicate that the medical device is enabled. In oneembodiment, second state 3406 initiates a power on reset (POR) to placethe electronic circuitry in one or more predetermined conditions. In oneembodiment, the medical device cannot be operated during the power onreset.

A transition 3410 occurs if the magnetic field coupled to the magneticsensitive switch falls below the threshold value before a firstpredetermined time period. Transition 3410 transitions the medicaldevice from second state 3406 to first state 3402. Thus, the medicaldevice goes from an enabled state to a disabled state. The magneticsensitive switch goes from being closed to open causing transition 3410.The detect circuit transitions from a detect=0 condition to a detect=1condition thereby disabling the switch. The power source is decoupledfrom the electronic circuitry as disclosed in first state 3402. Thelight emitting diode also is turned off in first state 3402. In theexample, the first predetermined time period is approximately 0.5seconds. The first predetermined time prevents inadvertent enabling ofthe device to an operative state due to a transient magnetic field.

A transition 3414 occurs if the magnetic sensitive switch remains in themagnetic field above the threshold value longer than the firstpredetermined time period. Transition 3414 transitions the medicaldevice from the second state 3406 to a third state 3412. In third state3412 the power source remains coupled to the electronic circuitry. Thelight emitting diode remains on indicating that the medical device isenabled. In the example, the power on reset is completed prior to thirdstate 3412 and the medical device can be made operational.

In general, third state 3412 occurs during a time period greater thanthe first predetermined time period but less than a second predeterminedtime period. Third state 3412 allows the medical device to be enabledand then disabled at a time of the users choosing. In one embodiment,the medical device remains enabled by removing the magnetic sensitiveswitch from the magnetic field prior to the end of the secondpredetermined period. A transition 3416 occurs when the magnetic fieldfalls below the threshold value. The magnetic sensitive switchtransitions from being closed to open due to the change in magneticfield. As shown in state diagram 3400, transition 3416 loops back onitself in third state 3412. Transition 3416 allows the medical device tostay in third state 3412 thereby keeping the switch enabled to maintaincoupling of the power source to the electronic circuitry. The detectcircuit detects the change in the magnetic sensitive switch and outputsa detect=1 condition. The light emitting diode also remains on toindicate that the medical device is enabled and being powered by theinternal power source. In the example, the second predetermined timeperiod is approximately 3 seconds. The second predetermined time periodprovides sufficient time for a physical action to occur such as movingthe medical device away from the magnetic field.

The medical device can be disabled in third state 3412 by exposing themagnetic sensitive switch to a magnetic field greater than the thresholdvalue. The magnetic sensitive switch closes when exposed to the magneticfield. The detect circuit detects the change in the magnetic sensitiveswitch and outputs a detect=0 condition. A transition 3418 transitionsfrom third state 3412 to first state 3402 when the detect circuitchanges to detect=0. In first state 3402, the power source is decoupledfrom the electronic circuitry. Removing power from the electroniccircuitry disables the medical device. The light emitting diode isturned off in first state 3402.

A transition 3422 occurs if the magnetic sensitive switch remains in themagnetic field greater than the threshold value for longer than thesecond predetermined time period. In the example, the magnetic sensitiveswitch is held within the magnetic field for a time period greater than3 seconds. Transition 3422 initiates a transition from third state 3412to a fourth state 3420. The magnetic sensitive switch has remained inthe closed position transitioning from first state 3402 to second state3406, from second state 3406 to third state 3412, and from third state3412 to fourth state 3420. Similarly, the detect circuit maintains adetect=0 condition through the multiple transitions. In fourth state3420, the switch remains enabled coupling the power source to theelectronic circuitry of the medical device. The state of the magneticsensitive switch is ignored after the transition to fourth state 3420.Thus, the power source can no longer be decoupled from the electroniccircuitry. The light emitting diode is turned off in fourth state 3420.As disclosed herein, the light emitting diode is emitting light insecond state 3406 and third state 3412. Turning off the light emittingdiode in fourth state 3420 indicates that the electronic circuitry willremained powered and the medical device cannot be turned off as it canbe from third state 3412. The power source voltage can be monitored asthe medical device is used. The power source will discharge over timeinitiating transition 3424. Transition 3424 occurs when a low voltage isdetected on the power source. Transition 3424 transitions from fourthstate 3420 to first state 3402. The switch is disabled in first state3402 thereby decoupling the power source from the electronic circuitryof the medical device. As mentioned previously, subsequent changes instate of the magnetic sensitive switch are ignored such that the medicaldevice remains in first state 3402.

A method of enabling a medical device is disclosed below. The steps ofthe method can be performed in any order. A non-limiting examplecomprising a spinal instrument having active circuitry for measuring aparameter, position, and trajectory is used to illustrate an enablingprocess. The method is applicable for medical devices having an internalpower source that can be stored for an extended period of time. Thepower source is decoupled during storage to maximize battery life andeliminate leakage paths that could discharge the power source. In oneembodiment, the power source cannot be replaced or recharged. Themedical device can be a disposable device that can be used for a singleapplication or until the power source can no longer support deviceoperation. The medical device may be sterilized and placed in sterilepackaging. The medical can be enabled while in the sterilized packagingusing the disclosed process thereby allowing interaction with the devicewithout affecting device sterility. In the example, the medical deviceis used intra-operatively in an operating room to support a surgicalprocedure and provide quantitative measurements on the muscular-skeletalsystem.

In a first step, a magnetic field above a threshold is detected by themedical device. In one embodiment, the medical device is placed on acradle having a magnet. The cradle can align or orient the medicaldevice in proximity to the magnet. The magnet field generated by themagnet exceeds the threshold value for enabling the medical device. Forexample, the cradle can hold a measurement device such as amuscular-skeletal instrument or a prosthetic component havingmeasurement apparatus therein. In a second step, a power source iscoupled to the electronic circuitry of the medical device. In theexample, the detected magnetic field enables a switch in the medicaldevice that couples the power source to the electronic circuitry. Thus,the electronic circuitry is enabled by the power source. In a thirdstep, providing power to the electronic circuitry initiates a power onreset. The power on reset can initialize internal states of electroniccircuitry in preparation of being used. Calibrations can also beperformed to ensure the medical device meets performance objectives. Forexample, the spinal instrument can be initialized for performing aworkflow on a spinal procedure and calibrated to ensure accuracy ofquantitative measurements such as load, load position, position in 3Dspace, and instrument trajectory. In a fourth step, the power source isdecoupled from the electronic circuitry when the magnetic field fallsbelow the threshold before a first time period. Thus, removing themedical device from the magnetic field within the first time periodallows the medical device to shut down.

In a fifth step, an indication of when the power source is coupled tothe electronic circuitry can be provided. For example, visual, audio, orhaptic means can be used to show the user a state of enablement of themedical device. In one embodiment, a light emitting diode on the medicaldevice can be used as an indicator. The light emitting diode can changefrom an off-state to an on-state when the power source is coupled to theelectronic circuitry of the medical device in the second step therebyindicating the medical device is being powered.

In a sixth step, the medical device is in the magnetic field above thethreshold for longer than the first time period. In a seventh step, thepower on reset is completed prior to the first time period expiring. Themedical device may be non-operational during the power on reset.

The medical device can be enabled and powered by the internal powersource for an extended period of time and then disabled at a time of auser choosing. The mode of operation where the medical device can beenabled and disabled is selected during a time period after the firsttime period but before a second time period expires. In an eighth step,it is detected that the magnetic field falls below the threshold afterthe first time period but less than the second time period. In anexample, the medical device can be removed from being in proximity to amagnet that generates the magnetic field thereby reducing the magneticfield below the threshold. As disclosed above, an example time firsttime period is approximately 0.5 seconds and the second time period isapproximately 3 seconds. Thus, the user would have 2.5 seconds to removethe medical device from the magnetic field. In a ninth step, indicationthat the power source is coupled to the electronic circuitry of themedical device is maintained. In the example, the light emitting diodewas emitting light when the power source was coupled to the electroniccircuitry to indicate the medical device is enabled. The light emittingdiode continues to emit light when the medical device is removed fromthe magnetic field after the first time period but before the secondtime period expires. The power on reset has been completed and themedical device is operable until it is disabled. In a tenth step, one ormore tests are performed on the medical device. Enabling the device asdisclosed above can be used to test or calibrate the device afterassembly while using the internal power source.

As mentioned previously, the medical device is enabled and operable ifremoved from the magnetic field after the first time period but beforethe second time period expires. In an eleventh step, a magnetic fieldabove the threshold is detected after the second time period expires. Inthe example, the medical device is enabled and operable. The detectionof the magnetic field above the threshold disables the medical device.In a twelfth step, the power source is decoupled from the electroniccircuitry. Decoupling the power source disables the medical device andminimizes leakage paths that can discharge the battery. In a thirteenthstep, decoupling of the power source from the electronic circuitry isindicated. In the example, the light emitting diode changes fromemitting light to being off thereby indicating the power source has beendecoupled and the medical device is disabled.

The medical device can be enabled such that the power source cannot bedecoupled from the electronic circuitry. This can be used for adisposable instrument or a device having a limited lifetime. In oneembodiment, the medical device has a power source capable of being usedfor a single procedure. The internal power source cannot be replaced orcharged. Maintaining the medical device in the magnetic field enablesthe mode of operation where the power source cannot be decoupled fromthe electronic circuitry. In a fourteenth step, the magnetic field isdetected above the threshold for a time period greater than the secondtime period. In the example, the medical device would be held inproximity to the magnetic field for greater than 3 seconds. In afifteenth step, detection of the magnetic field is disabled. In oneembodiment, changes in magnetic field above and below the threshold areignored. The power source remains coupled to the electronic circuitry.The medical device is enabled until the power source can no longersupport operation. Furthermore, the medical device can no longer beaffected by changes magnetic fields above and below the threshold. In asixteenth step, indication is provided that the power source remainscoupled to the electronic circuitry. The light emitting diode can changefrom emitting light to turning off when the medical device is held inthe magnetic field for longer than the second time period therebyindicating that the power source can no longer be decoupled from theelectronic circuitry.

The power source will eventually discharge over time either due tooperation of the medical device or leakage current. In a seventeenthstep, an under voltage condition is detected. The medical device may notperform as required when the voltage on the power source falls below apredetermined voltage. In an eighteenth step, the medical device is shutdown when the under voltage condition is detected. Shutting down themedical device prevents further measurement or operation of theinstrument from being performed. The power source may continue todischarge reducing the voltage further. Alternatively, the power sourcemay be decoupled from the electronic circuitry. The medical device isinoperable and may no longer be used. In a nineteenth step, the medicaldevice is disposed of. The medical device may be disposed of as ahazardous material or destroyed after use to prevent further usage.

While the present invention has been described with reference toparticular embodiments, those skilled in the art will recognize thatmany changes may be made thereto without departing from the spirit andscope of the present invention. Each of these embodiments and obviousvariations thereof is contemplated as falling within the spirit andscope of the invention.

What is claimed is:
 1. A method of enabling an orthopedic medical devicehaving an internal power source comprising: placing the orthopedicmedical device in proximity to a magnetic field above a threshold;maintaining the orthopedic medical device within the magnetic field forgreater than a predetermined time period where a magnetic sensitiveswitch is configured to change state when the orthopedic medical deviceis within the magnetic field, where the magnetic sensitive switchcouples to a delay circuit, where the delay circuit is configured tomeasure a delay of the predetermined time period after the magneticsensitive switch changes state; logic circuitry enabling a switch afterthe first time period where the switch couples a power source toelectronic circuitry, where the delay circuit couples to logiccircuitry, where the logic circuitry couples to the switch, and wherethe logic circuitry is configured to enable the switch when the delaycircuit measures the delay of the predetermined time period, the switchconfigured to couple the power source to electronic circuitry in themedical device when the switch is enabled; indicating that theorthopedic medical device is enabled by visual, audible, or hapticfeedback upon coupling the power source to the electronic circuitry inthe medical device; and the logic circuitry ignoring further changes inthe magnetic field after the first time period where the logic circuitryis configured to keep the switch enabled after the predetermined timeperiod.
 2. The method of claim 1 further including a step of decouplinga power source from a leakage path to prevent discharge of the powersource prior to use of the orthopedic medical device.
 3. A method ofenabling an orthopedic medical device comprising the steps of: amagnetic sensitive switch detecting when the orthopedic medical deviceis within a magnetic field is above a threshold where the magneticsensitive switch is configured to change state when the orthopedicmedical device is within the magnetic field; a delay circuit measuring atime period the orthopedic medical device is within the magnetic fieldabove the threshold where the magnetic sensitive switch couples to thedelay circuit, where the delay circuit is configured to detect thechange of state of the magnetic sensitive switch and where the delaycircuit is configured to measure when the magnetic sensitive switch hasbeen within the magnetic field greater than a first time period; logiccircuitry enabling a switch to couple a power source to electroniccircuitry of the orthopedic medical device when the time period isgreater than the first time period, where the delay circuit couples tothe logic circuitry, where the logic circuitry couples to the switch,and where the logic circuitry is configured to enable the switch whenthe delay is greater than the first time period as measured by the delaycircuit; the electronic circuitry initiating a power on reset of theelectronic circuitry to initialize internal states of the electroniccircuitry of the orthopedic medical device; and indicating that theorthopedic medical device is enabled by visual, audible, or hapticfeedback upon coupling the power source to the electronic circuitry inthe medical device.
 4. The method of claim 3 further including the stepsof: removing the orthopedic medical device from the magnetic fieldbefore the first time period where the magnetic sensitive switch changesstate; the delay circuit responsive to the magnetic sensitive switchwhere the delay circuit measures that the medical device is removedbefore the first time period; and logic circuitry responsive to thedelay circuit where the logic circuitry is configured to disable theswitch when the medical device is removed from the magnetic field beforethe first time period where the switch is configured to decouple thepower source from the electronic circuitry.
 5. The method of claim 3further including the steps of: removing the medical device from themagnetic field after a second time period where the second time periodis greater than the first time period where the magnetic sensitiveswitch changes state; the delay circuit responsive to the magneticsensitive switch where the delay circuit measures that the medicaldevice is removed after the second time period; and logic circuitryresponsive to the delay circuit where the logic circuitry is configuredto keep the switch enabled and where the switch maintains the powersource coupled to the electronic circuitry of the medical device.
 6. Themethod of claim 3 further including the steps of: removing theorthopedic medical device from the magnetic field after the first timeperiod but less than a second time period, where the magnetic sensitiveswitch is configured to change state when the medical device is removedfrom the magnetic field, where the delay circuit is configured to detectif the orthopedic medical device has been in the magnetic field for atime period greater than the first time period but less than the secondtime period; and logic circuitry responsive to the delay circuit wherethe logic circuitry is configured to keep the switch enabled and wherethe switch maintains the power source coupled to the electroniccircuitry of the medical device.
 7. The method of claim 6 furtherincluding a step of performing one or more tests on the orthopedicmedical device.
 8. The method of claim 6 further including the steps of:replacing the orthopedic medical device in a magnetic field where themagnetic sensitive switch changes state; the delay circuit responsive tothe magnetic sensitive switch; and disabling the switch wherein thepower source is decoupled from the electronic circuitry where the logiccircuitry is responsive to the delay circuit and where the logiccircuitry disables the switch when the medical device is placed back inthe magnetic field after having been previously removed from themagnetic field after the first time period but before the second timeperiod.
 9. The method of claim 3 further including the steps of:detecting when a voltage of the power source is below a minimum voltage,where the logic circuitry is configured to monitor the voltage of thepower source; and shutting down the orthopedic medical device when thevoltage is below the minimum voltage where the logic circuitry isconfigured to disable the switch thereby decoupling the power sourcefrom the electronic circuitry.
 10. The method of claim 3 furtherincluding a step of disposing of at least a portion of the orthopedicmedical device.